Question

i need help finding the intercepts Y=-2x^3+8x

Answer 1

Can you factor the equation?

Answer 2

x(-2x^2+8)

Answer 3

y = x(-2x^2+8)

So y is 0 when the graph cuts the x-axis

0 = x(-2x^2+8)

Cany you solve?

Answer 4

that's where i got stuck

Answer 5

is it -8=x(-2x^2) ?

Answer 6

Welll, we have two things multiplied together and result is zero so what that means?

Answer 7

Means one or both things are zero, right?

Answer 8

right
x=0

Answer 9

That's your first intercept.

Answer 10

Now put the other part equal to 0

Answer 11

-2x^2+8=0

Answer 12

Can you solve?

Answer 13

is it (-2x+8)(-2x-8)=0 ?

Answer 14

-2x^2+8=0 ->

2x^2 = 8 ->

x^2 = 4 -> and so

x= ?

Answer 15

but if you move the 8 to the right wouldn't it be negative?

Answer 16

@estudier

Answer 17

I moved the 2x^2 and then turned it around......

Answer 18

ah so x=2 right

Answer 19

It's the same, you can do it your way and then multiply both sides by -1

Answer 20

x is plus or minus 2

Answer 21

positive 2

Answer 22

I am saying it is both........

Answer 23

so the intercepts are (0,0) (-2,0) and (2,0)

Answer 24

Yup....

Answer 25

wow ok thank you so much estudier!!!