Question

@Intrinix One x-intercept for a parabola is at the point (-3,0). Use the factor method to find the other x-intercept for the parabola defined by this equation: y=-x^2-5x-6
Seperate the values with a comma.

Answer 1

can you show me how to the x-intercept now please

Answer 2

@extrinix

Answer 3

i have no idea do i use the quadrativ formula for this one

Answer 4

what do i do next because i dont remember doing it this way in class

Answer 5

i think they made us solve it using the quadratic formula- [y=\frac{ -b+\sqrt{b^2-4(ac)} }{ 2(a) }\]

Answer 6

\(y=\frac{-b+\sqrt{b^2-4(ac)}}{2a}\)

\(y=\frac{-(-5)+\sqrt{(-5)^2-4(-1)(-6)}}{2(-1)}\)

So we would simplify it
\(y=\frac{5+\sqrt{1}}{-2}\)

What would this equal?

Answer 7

See how that wouldn't work?

Because that's looking for the \(y-int\), not \(x-int\)

Answer 8

it would equal -3

Answer 9

Exactly, and that's the y-int we got the other day

Answer 10

oh

Answer 11

So we would do it by factoring

\(0=-x^2-5x-6\) Add \(-x^2-5x-6\) to both sides (to flip it)
\(x^2+5x+6=0\)

So what multiplies to get 6 and adds to get 5?
__ \(\times\) __ = 6
__ \(+\) __ = 5

Answer 12

3*2=6
3+2=5

Answer 13

Which would give us
\((x+3)(x+2)\)

So now we set each \(()\) equal to zero and solve for both of them
\(x+3=0\) | \(x+2=0\)

So what would you get?

Answer 14

-3,-2

Answer 15

So those are your two x-intercepts

Answer 16

so (-3,-2)

Answer 17

And you already have \((-3,0)\), so what would the other one be?

Answer 18

No, x-int is \((x,0)\), remember?

Answer 19

ok (-2,0

Answer 20

Correct