Question

find the x-intercept for
-16x^2+25x+10

Answer 1

I got to
0=16x^2+25x+10, then I tried using the quadratic formula; I got to
-25 +/-sqrt(1265)

Answer 2

(-25 +/-sqrt(625-4(-16)(10))/-32
(-25 +/- sqrt(625+640))/-32
(-25 +/- sqrt(1265)/-32

I can't square root 1265, and I can't solve by factoring.

Answer 3

am I forgetting a another equation that can solve this?

Answer 4

-16x^2+25x+10

x=[-b +-sq root(b^2 - 4*a*c)] / 2*a

x = [-25 +-sq root(625 -(4*-16*10))] / -32

x = [-25 +- sq root (625 - (-640)] / -32

x = [-25 +- sq root (1,265)] / -32

That's what I have so far.

Answer 5

sq root of 1,265 = 35.5668384876

Answer 6

yeah
I'm not exactly sure what to do from here... I need to simplify, but is there a way to do so? I get a big number if I square root the 1625... I'm not sure if the teacher would want that honestly.

Answer 7

I'm sot sure exactly how I can factor 1625 into a simplified square root.

Answer 8

You mean 1,265 right?

Answer 9

yeah.

Answer 10

I was thinking about simplifying the square root, like how you can with 50;
sqrt(50)->sqrt(25*2)->5sqrt(2)
but I can't find a factor of 1625 that would work

Answer 11

By the way 1265 factors into 5 * 11 * 23 so there's NO squares you could use there.

Well the question asks to find the x-intercepts.

The x-intercepts will not always be some "neat" 3 * sq root (7) type of answer.

Answer 12

hm... the teacher never specified which would be better as an answer...
I suppose then working throughout with decimals would be the answer?

Answer 13

I guess the best you could reduce that is
[ -25 ± Sq Root ( 1,265 ) ] / -32
I'd say you could show this but also showing a decimal answer would be advisable.

Answer 14

ok thank you so much!

Answer 15

Okay - u r welcome