Maths-
General
Easy

Question

Let a, b, c and x be real numbers. How is solving vertical line a x vertical line plus b equals c different from solving vertical line a x plus b vertical line equals c

The correct answer is: x=-(b+c)/a,-(b-c)/a Finally, we can observe that the solutions we get from the two given equations are different.


    Hint:
    |x| is known as the absolute value of x. It is the non-negative value of x irrespective of its sign. The value of absolute value of x is given by
    vertical line x vertical line equals open curly brackets table attributes columnalign right left right left right left right left right left right left columnspacing 0em 2em 0em 2em 0em 2em 0em 2em 0em 2em 0em end attributes row cell negative x comma x less than 0 end cell row cell x comma x greater or equal than 0 end cell end table close
    The symbol |.| is pronounced as ‘modulus’. We read |x| as ‘modulus of x’ or ‘mod x’.
    We discuss both these cases for the two given equations.
    Step by step solution:
    The first equation is
    |ax| + b = c
    Applying the definition of the modulus for ax in the above equation, we get
    For ax < 0, we have
    -ax + b = c
    Solving for x, we get
    x equals fraction numerator b minus c over denominator a end fraction
    For ax ≥ 0, we have
    ax + b = c
    Solving for x, we get
    x equals fraction numerator c minus b over denominator a end fraction
    Thus, we get two solutions for x,
    x equals fraction numerator b minus c over denominator a end fraction comma negative fraction numerator b minus c over denominator a end fraction
    The second equation is
    |ax + b| = c
    We use the definition of modulus,
    For ax + b < 0, we have
    -(ax + b)=c
    Solving for x, we get
    x equals negative fraction numerator b plus c over denominator a end fraction
    For ax + b ≥ 0, we have
    ax + b = c
    Solving for x, we get
    x equals negative fraction numerator b minus c over denominator a end fraction
    Thus, the two solutions we get are
    x = negative fraction numerator b plus c over denominator a end fraction comma negative fraction numerator b minus c over denominator a end fraction
    Finally, we can observe that the solutions we get from the two given equations are different.
    Note:
    In the first equation, mod changes the value of only one term, i.e., ax; whereas in the second equation, mod changes the value two terms, ax and b. This results in the change in values of x for both equations.

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