Question

Graph the function. Label the vertex and axis of symmetry. y=x^2-8x-20

Answer 1

Please explain.

Answer 2

find the factors of 20, that will add up to 8

Answer 3

so y=(x-10) (x-2)? Then what?

Answer 4

OK.. check the sign. x-10= 0; x + 2 = 0 ; where y =0

Answer 5

solve for x

Answer 6

x=10 and x =-2

Answer 7

got that

Answer 8

the vertex is at the midpoint , so it's between 10 and -2..... imagine a parabola. Mx= -2+10/2

Answer 9

Mx=8/2=4 so X =4; put in the original formula to find the corresponding My.

Answer 10

wait what?

Answer 11

You need the midpoint. that will be the vertex, (x,y) and the axis of symmetry will run straight down that point.

Answer 12

Plug in the x=4 to get the y.
y=x^2-8x-20

Answer 13

midpoint means add the two numbers and simply divide by 2, half it.

Answer 14

But theres two xs, sorry im so confused missed this lesson in class because i was sick

Answer 15

OK...

Answer 16

between those two x's is a third x. that is the midpoint you are looking for. Now I'll call it x3; so x3= x1 + x2/ 2

Answer 17

okay so 6

Answer 18

no, -2 +10/2= 8/2=4

Answer 19

the 2 is negative, -2

Answer 20

okay

Answer 21

now find y

Answer 22

You'll have 3 points and can now sketch the graph.

Answer 23

y=-36?

Answer 24

yes.

Answer 25

do you know what the graph looks like?

Answer 26

no, haha.