math check
posted by Stacey .
Simplify each rational expression.
3a(a4)^2 over a^2(a4) I don't understand how the answer would be 3(a4) over a because the a4 would cancel out???
4y^2 over y^22y once I simplify I get (2y)(2+y) over (y2)(y+2) I don't understand how the answer is (y+2) over y
9r^2 over r^23 once I simplify i get (3r)(3+r) over (r3)(r+3) I don't understand how the answer is (r+3) over r

3a(a4)^2 over a^2(a4)
3a(a4)(a4) over a*a*(a4)
You are correct that an (a4) would cancel, but you are left with another one because the top had the power of two on it. In addition, 1 a would also cancel, leaving you with 3(a4)/a
4y^2 over y^22y
Rewrite the numerator in standard form
y^2+4 and then factor out a 1, leaving you with 1(y^2  4) which then factors into: 1(y+2)(y2)
Then the denominator factors into:
y(y2). As a result, the (y2) factors cancel, leaving you with 1(y+2)/y
9r^2 over r^23
(Is the denominator supposed to be r^23r?)
Again, rewrite: r^2+9 > 1(r^29) > then as 1(r+3)(r3)
Denominator: r(r3)
Cancel out the (r3)'s and you are left with (r+3)/r