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).