The graph of the function f(x) = ax2 + bx +c (where a, b, and c are real and non zero) has two x-intercepts. Explain how to find
1 answer:
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9514 1404 393
Answer:
(b) -36
Step-by-step explanation:
Synthetic division is often performed using a table of the kind shown in the attachment. The coefficients of f(x) are placed across the top, and the x-value to be evaluated is placed at the left. The rule for finding table entries is shown. (The first (left-most) number at the bottom is the leading coefficient of the polynomial.)
This table shows the remainder, which is f(-2), is -36.
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The equation itself can be rewritten in "Horner form" to facilitate evaluation.
f(x) = (((-x +2)x -1)x +4)x +8
In this form, substituting for x and doing the evaluation is easier for mental arithmetic. You will notice that the contents of parentheses at each level match the bottom line of the synthetic division table.
f(-2) = (((-(-2) +2)(-2) -1)(-2) +4)(-2) +8
= (((4)(-2) -1)(-2) +4)(-2) +8
= ((-9)(-2) +4)(-2) +8
= (22)(-2) +8
= -36
f(-2) = -36 . . . . remainder from synthetic substitution
