Expert: Scott A Wilson - 11/27/2009

Question
question:
1- (a-5) (4a+7)
I believe the answer equals 4a^2-35 is this answer correct?

2- (x-y) (3x+y-3) I believe the answer equals 3x^2y+y^2x-3xy is this correct?  

Answer
1. You multiplied the left * left and got a•4a=4a² the right * right and got -5•7=-35,
but you also need to cross multiply and get a•7 - 5•4a = 7a - 20a = -13a.

2. Multiply the x be 3x, y, and -3, and then mulitply -y times 3x, y, and -3.
Add together any like terms.

That should give you 3x² + xy - 3x - 3xy - y² + 3y.
The only like terms I see are the +xy - 3xy.  Combine those and rewrite.