Question

solve for y: y^2-3y=18

Answer 1

Subtract 18 and factor,
\[y^2-3y-18\]

Answer 2

I'm confused @bibby

Answer 3

(Two of 18's factors are 3 and 6)
Do you know how to factor quadratics?

Answer 4

y = 3, y = -6
y = 3, y = 6
y = -3, y = 6

Answer 5

I'm not going to just give you the answer. What combination of 6 and 3 gives you -3?

Answer 6

I'm not looking for the answer. I'm showing you the factors

Answer 7

So plug them in. I've given you everything you need. Factor the following:

\[y^2-3y-18\]

Answer 8

I have to subtract (-6)-3 in order to get -3 right?

Answer 9

Close. that'd give you -9

To get -3 you can use 3-6 or -6+3. and so we now have

(y+3)(y-6) or (y-6)(y+3) either way it's the same thing
Set that equal to 0 and solve

Answer 10

Wait.. that will equal -9

Answer 11

-6+3 right?

Answer 12

Yeah :D

Answer 13

Thanks.. Can you help me with another one if you don't mind?

Answer 14

uh sure. if you could give me a medal that'd be pretty sweet too.

Answer 15

@bibby did i do it right?

Answer 16

uhhh what'd you do?

Answer 17

the medal?

Answer 18

Oh, yeah. Thanks!

Answer 19

Solve using the quadratic formula