Question

using the quadratic formula find the x-intercepts. the problem is 3.2x^2-6.4x-25.8
i cant seem to get the answers like in the book.. i need help with step by step

Answer 1

Hmm first do you know what is the quadratic formula?

Answer 2

yes i do know

Answer 3

Probably a careless mistake, awaiting Callisto's reply!

Answer 4

To find the x-int.
put the equation =0
3.2x^2-6.4x-25.8 =0
Apply the quadratic formula,
\[x= \frac{-b\pm\sqrt{b^2-4ac}}{2a}\]
Put, a=3.2, b=-6.4 and c= -25.8 into the formula
\[x= \frac{-(-6.4)\pm\sqrt{(-6.4)^2-4(3.2)(-25.8)}}{2(3.2)} =\frac{6.4\pm\sqrt{371.2}}{2(3.2)} = ..?\]

Answer 5

im still doing something wrong i got to that part. and i still dont get the right answer. what am i doing wrong. i know that there is something that i am either missing or did completely wrong. the answers are suppose to be 4.0104 and -2.0104

Answer 6

most likely your signs..
what did you get for (-6.4)^2

Answer 7

-40.96

Answer 8

that's the problem...

Answer 9

miss2ne2 i suggest you continue the workings from where Callisto left off. then we can tell you where u made the mistake. I calculated and confirm the working of Callisto is correct up to that point.

Answer 10

should be positive 40.96

Answer 11

i ment i got the positive. i just checked but i still am lost

Answer 12

how the hell you all get 40.96.

Answer 13

mind your language son...

Answer 14

exactly you dont have to be rude about it

Answer 15

Sorry. habit i guess.

Answer 16

I don't mean anything offensive. My bad

Answer 17

callisto's solution is correct. i think it is just calculation errs...

Answer 18

we got the 40.96 because in the quadratic formula you have to square it. and dont worry about it.

Answer 19

i got to that last part. i get it up to there but from there im lost.