# How do you find the x-intercepts of the equation f(t) = -16t^2 - 64t 80?

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I've already factored it out to f(t) = -16(t - 1)(t - 5), but I'm unsure what to do from there.

Jul 31st, 2015

First there is no x in the equation. Secondly if there is, then the equation will be

f(x) = - 16(x - 1)(x - 5)

y = - 16(x - 1)(x - 5)

So

To find x intercept, we put y = 0 then

0 = - 16(x - 1)(x - 5)

(x - 1)(x - 5) = 0

x - 1 = 0     ,     x - 5 = 0

x = 1         ,        x = 5

Hence x intercepts are 1 and 5

Jul 31st, 2015

When I graphed the equation on Desmos, it showed that the x-intercepts were -5 and 1.

Jul 31st, 2015
wowow.jpg

f(t) = -16t^2 - 64t + 80

f(t) = - 16(t^2 + 4t - 5)

f(t) = - 16(t^2 - t + 5t - 5)

f(t) = - 16(t(t - 1) + 5(t - 1))

f(t) = - 16(t - 1)(t + 5)

So as I have done the factorization and I see that you've done wrong factorization. So

The graph is right. And using the factored term, the x intercepts are 1 and - 5.

Jul 31st, 2015

Okay?

Jul 31st, 2015

Yep! Got it.

Jul 31st, 2015

Okay.

Jul 31st, 2015

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Jul 31st, 2015
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Jul 31st, 2015
Nov 21st, 2017
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