solve the quadratic equation: x2-2x-15=0.

Question

solve the quadratic equation:  x2-2x-15=0.

lgbasallote · Answer

break down the middle term

$$\implies x^2 - 5x + 3x - 15 = 0$$
now factor it out

does that help @MusicTeacher ?

dumbcow · Answer

are you really a music teacher?

anyway you can also use the quadratic formula here

anonymous · Answer

yes i am actually a music teacher :)  20+ years

anonymous · Answer

Basically, i would just do "factors of 15" and they are 1 and 15, 3 and 5, and depending on the middle term, since it's negative 2, it has to be (x-5)(x+3) if that makes it more simple
since the x^2 has a "1" in front of it

anonymous · Answer

ok i got this now!  ty!! it isn't so hard as it seems,,,,

anonymous · Answer

Yeah, it's not that bad, it's simple when the last term can be factored, only use the quadratic if the factored values do not match up.

anonymous · Answer

great ty!

dumbcow · Answer

very cool..too bad i can't trade some of my math skills for some of your musical talent :)

anonymous · Answer

:)  i only wish,,,, i need a lot of help!  trying to learn geometry by myself,,,,