Posted by Cora on .
Hi! I was wondering if anyone might be willing to check my answers for these... I have a suspiscion they are wrong, but I don't have any correct answers to compare them against. If I got them wrong, would you mind giving a brief explanation? Thank you for your help! (x^21)+(2x+3) (I got 2x+x^2+2).
(X^21) (x^2+9) (I got x^3+12)
(x^2+9)(x+3) (I got x+12)
f(g(x)) F=3x4 G=(x^2)I got 3x^3+4x^2
f(g(x))F=2x G+2x^2+3 I got 4x^3+6x

Algebra 
drwls,
Your answers almost seem like wild guesses. You appear to be in serious need of private tutoring until you grasp basic algebraic rules.
Why do you have both a + and in front of the 9 in the first problem and in front of the 3 in the second problem?
(x^21) (x^29) = x^4  10x^2 +9
x^2 9 (x 3) = x^2 x 6
If f=3x4 and g=(x^2)
f[g(x)] = 3x^2 4
g[f(x)] = (3x4)^2 =9x^2 +24x 16