Maths-
General
Easy

Question

If (m+n) P2 = 56 and m–nP2 = 12 then (m, n) equals-

  1. (5, 1)    
  2. (6, 2)    
  3. (7, 3)    
  4. (9, 6)    

hintHint:

U sin g space f o r m u l a comma space e x p a n d space t h e space a b o v e space g i v e n space e q u a t i o n s
P presuperscript n subscript r space equals space space fraction numerator n factorial over denominator left parenthesis n minus r right parenthesis factorial end fraction
a n d space s i m p l i f y

The correct answer is: (6, 2)


    G i v e n space colon space P presuperscript left parenthesis m plus n right parenthesis end presuperscript subscript 2 equals space 56 space a n d space space P presuperscript m minus n end presuperscript subscript 2 space equals space 12

U sin g space f o r m u l a comma space e x p a n d space t h e space a b o v e space g i v e n space e q u a t i o n s
P presuperscript n subscript r space equals space space fraction numerator n factorial over denominator left parenthesis n minus r right parenthesis factorial end fraction

P presuperscript left parenthesis m plus n right parenthesis end presuperscript subscript 2 equals space 56
rightwards double arrow fraction numerator left parenthesis m plus n right parenthesis factorial over denominator left parenthesis m plus n minus 2 right parenthesis factorial end fraction equals space 56
rightwards double arrow fraction numerator left parenthesis m plus n right parenthesis space left parenthesis m plus n minus 1 right parenthesis space left parenthesis m plus n minus 2 right parenthesis factorial over denominator left parenthesis m plus n minus 2 right parenthesis factorial end fraction equals space 56
rightwards double arrow left parenthesis m plus n right parenthesis space left parenthesis m plus n minus 1 right parenthesis space equals space 56 space

L e t space m space plus space n space equals space t

rightwards double arrow left parenthesis t right parenthesis space left parenthesis t minus 1 right parenthesis space equals space 56 space
rightwards double arrow t squared space minus space t space minus 56 space equals space 0

O n space f a c t o r i z i n g space b y space s p l i t t i n g space o f space m i d d l e space t e r m s
rightwards double arrow left parenthesis t minus 8 right parenthesis left parenthesis t space plus space 7 right parenthesis space equals space 0
rightwards double arrow space t space equals space 8 comma space minus 7 space left parenthesis n e g a t i v e space v a l u e space c a n n o t space b e space t a k e n right parenthesis
rightwards double arrow space t space equals space 8
rightwards double arrow space m space plus space n space equals space 8 space........ space left parenthesis 1 right parenthesis
    Similarly
    P presuperscript left parenthesis m minus n right parenthesis end presuperscript subscript 2 equals space 12
rightwards double arrow fraction numerator left parenthesis m minus n right parenthesis factorial over denominator left parenthesis m minus n minus 2 right parenthesis factorial end fraction equals space 56
rightwards double arrow fraction numerator left parenthesis m minus n right parenthesis space left parenthesis m minus n minus 1 right parenthesis space left parenthesis m minus n minus 2 right parenthesis factorial over denominator left parenthesis m minus n minus 2 right parenthesis factorial end fraction equals space 12
rightwards double arrow left parenthesis m minus n right parenthesis space left parenthesis m minus n minus 1 right parenthesis space equals space 12

L e t space m minus space n space equals space a

rightwards double arrow left parenthesis a right parenthesis space left parenthesis a minus 1 right parenthesis space equals space 12 space
rightwards double arrow a squared space minus space a space minus 12 space equals space 0

O n space f a c t o r i z i n g space b y space s p l i t t i n g space o f space m i d d l e space t e r m s
rightwards double arrow left parenthesis a minus 4 right parenthesis left parenthesis a space plus space 3 right parenthesis space equals space 0
rightwards double arrow space a space equals space 4 comma space minus 3 space left parenthesis n e g a t i v e space v a l u e space c a n n o t space b e space t a k e n right parenthesis
rightwards double arrow space a space equals space 4
rightwards double arrow space m space minus space n space equals space 4 space........ space left parenthesis 2 right parenthesis


    Adding (1) and (2), we get
    2 m space equals space 12
rightwards double arrow space m space equals space 6

    Substituting m= 6 in (2), we get
    6 minus n space equals space 4
rightwards double arrow n equals 2
     Thus, If P presuperscript left parenthesis m plus n right parenthesis end presuperscript subscript 2 equals space 56 and P presuperscript m minus n end presuperscript subscript 2 then (m, n) equals- (6,2)

    Related Questions to study

    General
    physics-

    A thin uniform annular disc (see figure) of mass M has outer radius 4 R and inner radius 3 R. The work required to take a unit mass from point P on its axis to infinity is

    A thin uniform annular disc (see figure) of mass M has outer radius 4 R and inner radius 3 R. The work required to take a unit mass from point P on its axis to infinity is

    physics-General
    General
    physics-

    The two bodies of mass m subscript 1 end subscript and m subscript 2 end subscript left parenthesis m subscript 1 end subscript greater than m subscript 2 end subscript right parenthesis respectively are tied to the ends of a massless string, which passes over a light and frictionless pulley. The masses are initially at rest and the released. Then acceleration of the centre of mass of the system is

    The two bodies of mass m subscript 1 end subscript and m subscript 2 end subscript left parenthesis m subscript 1 end subscript greater than m subscript 2 end subscript right parenthesis respectively are tied to the ends of a massless string, which passes over a light and frictionless pulley. The masses are initially at rest and the released. Then acceleration of the centre of mass of the system is

    physics-General
    General
    maths-

    If x equals 1 plus 3 a plus 6 a squared plus 10 a cubed plus midline horizontal ellipsis. to straight infinity terms, vertical line a vertical line less than 1 comma y equals 1 plus 4 a plus 10 a squared plus 20 a cubed plus midline horizontal ellipsis straight infinity terms, vertical line a vertical line less than 1, then x colon y

    If x equals 1 plus 3 a plus 6 a squared plus 10 a cubed plus midline horizontal ellipsis. to straight infinity terms, vertical line a vertical line less than 1 comma y equals 1 plus 4 a plus 10 a squared plus 20 a cubed plus midline horizontal ellipsis straight infinity terms, vertical line a vertical line less than 1, then x colon y

    maths-General
    parallel
    General
    Maths-

    The coefficient of x to the power of negative n end exponent in left parenthesis 1 plus x right parenthesis to the power of n end exponent open parentheses 1 plus fraction numerator 1 over denominator x end fraction close parentheses to the power of n end exponent is

    The coefficient of x to the power of negative n end exponent in left parenthesis 1 plus x right parenthesis to the power of n end exponent open parentheses 1 plus fraction numerator 1 over denominator x end fraction close parentheses to the power of n end exponent is

    Maths-General
    General
    maths-

    open parentheses 1 plus x plus x squared plus horizontal ellipsis plus x to the power of p close parentheses to the power of n equals a subscript 0 plus a subscript 1 x plus a subscript 2 x squared plus horizontal ellipsis plus a subscript n p end subscript x to the power of n p end exponent not stretchy rightwards double arrow a subscript 1 plus 2 a subscript 2 plus 3 a subscript 3 plus horizontal ellipsis plus n p

    open parentheses 1 plus x plus x squared plus horizontal ellipsis plus x to the power of p close parentheses to the power of n equals a subscript 0 plus a subscript 1 x plus a subscript 2 x squared plus horizontal ellipsis plus a subscript n p end subscript x to the power of n p end exponent not stretchy rightwards double arrow a subscript 1 plus 2 a subscript 2 plus 3 a subscript 3 plus horizontal ellipsis plus n p

    maths-General
    General
    chemistry-

    Compounds (A) and (B) are – 

    Compounds (A) and (B) are – 

    chemistry-General
    parallel
    General
    Maths-

    2 times C subscript 0 plus 5 times C subscript 1 plus 8 times C subscript 2 plus horizontal ellipsis plus left parenthesis 2 plus 3 n right parenthesis times C subscript n equals

    2 times C subscript 0 plus 5 times C subscript 1 plus 8 times C subscript 2 plus horizontal ellipsis plus left parenthesis 2 plus 3 n right parenthesis times C subscript n equals

    Maths-General
    General
    maths-

    A triangle is inscribed in a circle. The vertices of the triangle divide the circle into three arcs of length 3, 4 and 5 units. Then area of the triangle is equal to:

    A triangle is inscribed in a circle. The vertices of the triangle divide the circle into three arcs of length 3, 4 and 5 units. Then area of the triangle is equal to:

    maths-General
    General
    Maths-

    If one root of the equation a x squared plus b x plus c equals 0 is reciprocal of the one of the roots of equation  a subscript 1 x squared plus b subscript 1 x plus c subscript 1 equals 0 then

    If one root of the equation a x squared plus b x plus c equals 0 is reciprocal of the one of the roots of equation  a subscript 1 x squared plus b subscript 1 x plus c subscript 1 equals 0 then

    Maths-General
    parallel
    General
    Maths-

    If the quadratic equation a x squared plus 2 c x plus b equals 0 and a x squared plus 2 b x plus c equals 0 left parenthesis b not equal to c right parenthesis have a common root then a plus 4 b plus 4 c is equal to

    If the quadratic equation a x squared plus 2 c x plus b equals 0 and a x squared plus 2 b x plus c equals 0 left parenthesis b not equal to c right parenthesis have a common root then a plus 4 b plus 4 c is equal to

    Maths-General
    General
    physics-

    Two blocks of masses 10 kg and 4 kg are connected by a spring of negligible mass and placed on frictionless horizontal surface. An impulsive force gives a velocity of 14m s to the power of negative 1 end exponent to the heavier block in the direction of the lighter block. The velocity of centre of mass of the system at that very moment is

    Two blocks of masses 10 kg and 4 kg are connected by a spring of negligible mass and placed on frictionless horizontal surface. An impulsive force gives a velocity of 14m s to the power of negative 1 end exponent to the heavier block in the direction of the lighter block. The velocity of centre of mass of the system at that very moment is

    physics-General
    General
    Maths-

    In a Δabc if b+c=3a then cot invisible function application straight B over 2 times cot invisible function application straight C over 2 has the value equal to –

    In a Δabc if b+c=3a then cot invisible function application straight B over 2 times cot invisible function application straight C over 2 has the value equal to –

    Maths-General
    parallel
    General
    Maths-

    In a capital delta A B C open parentheses fraction numerator a to the power of 2 end exponent over denominator sin invisible function application A end fraction plus fraction numerator b to the power of 2 end exponent over denominator sin invisible function application B end fraction plus fraction numerator c to the power of 2 end exponent over denominator sin invisible function application C end fraction close parentheses times s i n invisible function application fraction numerator A over denominator 2 end fraction s i n invisible function application fraction numerator B over denominator 2 end fraction s i n invisible function application fraction numerator C over denominator 2 end fraction simplifies to

    In a capital delta A B C open parentheses fraction numerator a to the power of 2 end exponent over denominator sin invisible function application A end fraction plus fraction numerator b to the power of 2 end exponent over denominator sin invisible function application B end fraction plus fraction numerator c to the power of 2 end exponent over denominator sin invisible function application C end fraction close parentheses times s i n invisible function application fraction numerator A over denominator 2 end fraction s i n invisible function application fraction numerator B over denominator 2 end fraction s i n invisible function application fraction numerator C over denominator 2 end fraction simplifies to

    Maths-General
    General
    Maths-

    In a triangle ABC, a: b: c = 4: 5: 6. Then 3A + B equals to :

    In a triangle ABC, a: b: c = 4: 5: 6. Then 3A + B equals to :

    Maths-General
    General
    physics-

    A bullet of mass m is fired with a velocity of 50 m s to the power of negative 1 end exponent at an angle theta with the horizontal. At the highest point of its trajectory, it collides had on with a bob of massless string of length l equals 10 divided by 3m and gets embedded in the bob. After the collision, the string moves to an angle of 120degree. What is the angle theta ?

    A bullet of mass m is fired with a velocity of 50 m s to the power of negative 1 end exponent at an angle theta with the horizontal. At the highest point of its trajectory, it collides had on with a bob of massless string of length l equals 10 divided by 3m and gets embedded in the bob. After the collision, the string moves to an angle of 120degree. What is the angle theta ?

    physics-General
    parallel

    card img

    With Turito Academy.

    card img

    With Turito Foundation.

    card img

    Get an Expert Advice From Turito.

    Turito Academy

    card img

    With Turito Academy.

    Test Prep

    card img

    With Turito Foundation.