how to factor

Question

r²=8-2r

Answer 1

Liv,

It looks like you have an equation to solve, and factoring will be part of that.  First, you want 0 on one side of the equation, so 

r² = 8 - 2r

r² + 2r - 8 = 0

Now you factor into two binomials. The leading coefficient is 1, so you know you have (r     ) (r     ).  You want to find two numbers that multiply to give you -8 and add to be 

+2.  Well, it's not 8 and -1.  B,  But if we look at 4 * 2, and the 4 is positive and the 2 negative, we will get the right middle term,

(r - 2) (r + 4) = 0   The set each factor to 0 and solve.

You can do it.

Mary