Question

Use the quadratic formula to find the x-intercepts of the function. Round to the nearest tenth, if necessary.
y = -2x2 + 5x - 1

Answer 1

the formula is

\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]

in your question a = -2, b = 5 and c = -1

\[x = \frac{-5 \pm \sqrt{5^2 - 4(-2)(-1)}}{2(-2)}\]

just evaluate

Answer 2

x = [ -5 +_ sqrt(5^2 - 4 *( -2) * (-1)] 2*(-2)

Answer 3

@Luis_Rivera... i get 5.5 and -3? Is that right?

Answer 4

No, not right.

Answer 5

Im confused

Answer 6

You should use your calculator and solve these two expressions:
1.\[1/4(5+\sqrt{17})\]2.\[1/4(5-\sqrt{17})\]

I believe that is what Luis_Rivera gave you.

Answer 7

Both answers will be positive.

Answer 8

I got 2.3 and 0.2. Is that right?

Answer 9

That sounds more better, let me see what I get on my calc' 2.28 and 0.219
Close enough I would say. Great.

Answer 10

Thanks! it starting to make more sense. (:

Answer 11

Luis_Rivera gave a very detailed step by step solution for you, it is a very good solution method.

Answer 12

I hope you were able to see his link.

Answer 13

Yes i was. BUt was still confused. :)

Answer 14

If you have any questions regarding his solution please ask them and I will attempt to answer.

Answer 15

I just didnt get the last part.. Like if i had to square 17 and +5 then divede by 4

Answer 16

Since you obtained correct answer, I believe you've got it now. Good luck.

Answer 17

Thanks! Yeah i get it now. :D