q(x)= x^2 + 9 r(x)= radical sign (x +8)

Question

(r • q)(8)=

(q • r)(8)=

It’s finding the composition of two functions. I’m confused on this problem.

Answer 1

R(Q(x)) = sqrt( x^2+9+8) = sqrt(x^2+17)

Q(R(x)) = X+8+9 = X+17

R(Q(8)) = sqrt(8^2+17) = sqrt(64+17) = sqrt(81) = 9

Also, Q(8) = 73 --> r(73) = sqrt(73+8) = sqrt(81) = 9, so yes it checks

Q(R(8)) = 8 +17 = 25

Also, R(8) = sqrt(8+8) = sqrt(16) = 4 --> Q(4) = 4^2+9 = 16+9 = 25,

so yes it checks