Question

check my answer please.
Suppose that the functions p and q are defined as follows.
p(x)=x^2+3
q(x)=sqrt(x+2)
find (q*p)(2)=[?] and (p*q)(2)=[?]
I got (q*p)(2)=sqrt 10 and (p*q)(2)=8

Answer 1

\[p(x)=x^2+3\]\[q(x)=\sqrt{x+2}\]
\[(qp)(x)=q(x) \times p(x)\]
\[pq(x)=p(x) \times q(x)\]
Since multiplication is commutative,
I don't understand how you are getting different answers

Answer 2

this could be a composite function question like
(q o p) (x) or (p o q)(x) ?

Answer 3

I was thinking that too, let me check your answers @Kimes

Answer 4

sorry yes (q o p) (x) or (p o q)(x) i the right format

Answer 5

I think your answers are incorrect @Kimes , both of them

Answer 6

well I followed the steps shown in my book, can you explain then

Answer 7

Can you show me your steps, how you've attempted the question?

Answer 8

(q o p)
q(p(2))
q(2^2+3)
q(7)
sqrt 7+3= sqrt 10

(p o q)
p(q(2))
p(sqrt 2+3)
p(sqrt 5)
(sqrt 5)^2+3=8

Answer 9

I see the mistake now, let me ask you first
what is your q(x)?
\[q(x)=\sqrt{x+2}\]
\[q(x)=\sqrt{x+3}\]
Because in the question you've said sqrt{x+2}
but in the solution you've used sqrt{x+3}

Answer 10

ahh I made a silly mistake! thanks for catching it!

Answer 11

You're welcome, your method of doing the question is perfectly fine, which is good as that means you've grasped the concept, only thing is you made a calculation mistake, that's not a big problem you just have to be careful