Question

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Evaluate the function g(x) = -2x² + 3x – 5 for the input values -2, 0, and 3.
g(-2) = -2(-2)2 + 3(-2) - 5
g(-2) = -2(4) - 6-5
g(-2) = ?
g(0) =?
g(3) =?

Answer 1

• g(-2) = -19
• g(0) = -5
• g(3) = -14

Explanation:

When you have several evaluations to do, it is often convenient to put the formula into a graphing calculator or spreadsheet.

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If you must evaluate a polynomial by hand, it is often easier if the expression is written in "Horner form":

g(x) = (-2x +3)x -5

Then we have ...

g(-2) = (-2(-2) +3)(-2) -5 = 7(-2) -5 = -19

g(0) = (-2(0) +3)(0) -5 = -5

g(3) = (-2(3) +3)(3) -5 = (-3)(3) -5 = -14