Question

Which point is an x-intercept of the quadratic function
f(x) = (x – 8)(x + 9)?

Answer 1

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Answer:  $\textsf{(8, 0) and (-9, 0)}$

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Given:  $\textsf{f(x) = (x - 8)(x + 9)}$

Find:  $\textsf{Determine the x-intecept}$

Solution:  In order to find the x-intercept we need to set the y-value to 0 which means that we are looking for the points that cross the x-axis.  Then we just solve for x and we get the x-intercepts.

Set y to 0

• $\textsf{f(x) = (x - 8)(x + 9)}$

• $\textsf{0 = (x - 8)(x + 9)}$

Determine the first x-intercept

• $\textsf{x - 8 + 8 = 0 + 8}$

• $\textsf{x = 0 + 8}$

• $\textsf{x = 8}$

Determine the second x-intercept

• $\textsf{x + 9 - 9 = 0 - 9}$

• $\textsf{x = 0 - 9}$

• $\textsf{x = - 9}$

There are two x-intercepts of the quadratic function that was provided which are (8, 0) and (-9, 0).