Thread: factoring quadratic eqations?

I'm so confused. How do you do these? I don't understand what to do with the number next to the x2. here's what I did. What am I doing wrong? Please help!
2x^2+10=9x
-9x -9x
2x^2=10-9x=0
-10 -10
2x^2-9x=-10
2 2
x^2-9x=-5
(x-10)(x+1)
x=-10,1

Originally Posted by megs94

I'm so confused. How do you do these? I don't understand what to do with the number next to the x2. here's what I did. What am I doing wrong? Please help!
2x^2+10=9x
-9x -9x
2x^2=10-9x=0
-10 -10
2x^2-9x=-10
2 2
x^2-9x=-5
(x-10)(x+1)
x=-10,1

I can't follow your working but I can see at least 1 mistake (you've divided some but not all terms by 2).

Re-arrange:

Factorise: (2x - 5)(x - 2) = 0.

Solve: x = 5/2, 2.

Theres a much easier way to do the factoring part. Cross factoring... if you can get the idea on how to do it, factoring is a breeze Read my post and comment if you'd like Factoring Quadratics for Idiots