Question
The graph of the function f is shown in the xy-plane above, where y =f . Which of the following functions could define f ?
Hint:
Hint:
First, we carefully observe the graph to find the zeroes of the function, that is, we find the points at which is 0. From there, we get the factors that appear in the equation of the graph. Then we check the multiplicity of each of these factors to get the final equation. By multiplicity, we mean the number of times each factor appears in the equation or we can say, multiplicity of a factor is the power of the factor in the equation. Also, the degree of the equation is one greater than the number of turning points in the graph. (Turning point means the point on the graph where the function turns from increasing to decreasing or vice-versa.)
The correct answer is:
By observing the graph, we see that the curve cuts the x-axis at three points. These points are given as
So is 0 at each of these three points.
Hence, the factors which appear in the equation are
Next, we find the multiplicity of each of these factors.
We know that if a graph bounces off the x-axis at a point, then the multiplicity of the factor associated with the point is even.
And if the graph crosses the x-axis through a point, then the multiplicity of the factor associated with the point is odd.
So, the multiplicity of ( x + 3) is odd and the multiplicity of ( x + 1 ) and ( x - 2 ) is even.
Clearly, there are four turning points on the graph, so the degree of the equation is 5.
Clearly, there are four turning points on the graph, so the degree of the equation is 5.
Thus, a possible function which defines the curve is given by
Here, the degree of the equation is 5(=1+2+2). The multiplicity of (x +3 ) is 1, which is odd and the multiplicity of (x + 1) and ( x- 2) is 2, which is even.
The correct option is C).
.
Note:
We need to know properties about factors, multiplicity, leading co-efficients and turning points to find out the function from a graph.
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Note:
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Note:
This question could also be solved by eliminating the options. Option A is wrong as the population k years after 1962 is 48, not 61. Option B is wrong because we find the value of k to be 32. Option C is wrong because the difference between the population in 1962 and the population k years after 1962 is given by 2000-48=1952.
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If a white birch tree and a pin oak tree each now have a diameter of 1 foot, which of the following will be closest to the difference, in inches, of their diameters 10 years from now? (1 foot = 12 inches)
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Note:
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In the equation above, c is a constant. If the equation has infinitely many solutions, what is the value of c ?
Note:
As the equation is true for all values of x, we could have put x equal to any other number instead of 1, and we would get the same result. If we put x=1 in the first step as well, we would get the same value for x