Question

Use the quadratic formula to find any x-intercepts on the graph of the equation. Type answer using radicals. y=4x^2-5x-4

Answer 1

Help....

Answer 2

Do you know the quadratic formula?

Answer 3

yes

Answer 4

x-intercept means you let y equal 0 then solve for x.
4x^2-5x-4=0
now use quadratic formula

Answer 5

so far I have x= -5+square root of 89/8, and I'm stuck

Answer 6

a = 4, b = -5, c = -4
\[x = \frac{-(-5) \pm \sqrt{(-5)^2 - 4($)(-4)}}{2(4)}\]
is that what you got at the beginning?

Answer 7

yes

Answer 8

then it should be \[x = \frac{5\pm \sqrt{89}}{8}\] so 5 should not be negative

Answer 9

-(-5) = +5

Answer 10

I do not understand how you got that answer

Answer 11

I'm stuck on the square root of 89

Answer 12

i don't think it can be simplified. 89 looks like prime. you can use a calculator to find the exact value of square root of 89 though

Answer 13

ok, i found that to be true as well, but wanted to double check. The final answer will be x=5+ square root of 89/4?

Answer 14

no. 5 plus/minus square root of 89/8 in other words
\(x = \frac{5 + \sqrt{89}}{8}\) and \(x = \frac{5-\sqrt{89}}{4}\)

Answer 15

Where are you getting 4 from in the denominator? Should be 8.

Answer 16

i got confused too. yeah second denominator should be 8