Question

Find y-intersection of x^2-12x+39 I've gotten myself lost -.-

Answer 1

what is it when x=0?

Answer 2

oh replace x with 0 to find y-intersection am i right?

Answer 3

yep; the y axis IS the x=0 axis; so when x=0 ..... where does it hit?

Answer 4

39

Answer 5

tada!!

Answer 6

:D im not very good at this, how about x?

Answer 7

the x intercepts are when y=0; which is tricker on quadratics

Answer 8

you gotta have an eye for factors of just plug in the quadratic formula

Answer 9

x^2-12x+39 = 0

x^2-12x = -39

x^2-12x+36 = -39+36

(x-6)^2 = -3

it dont hit the x axis by this

Answer 10

ok let me check over thios

Answer 11

http://www.wolframalpha.com/input/?i=x^2-12x%2B39

Answer 12

you're awesome!

Answer 13

.. yep

Answer 14

Oh where did you get the 36 in the 3rd line above?

Answer 15

its called completing the square: in a nutshell its just taking that number on the "x" and halving it; then squareing it