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Suppose that the functions [tex] q [/tex] and [tex] r [/tex] are defined as follows.

[tex]\[
\begin{array}{l}
q(x) = x^2 + 6 \\
r(x) = \sqrt{x + 9}
\end{array}
\][/tex]

Find the following.

[tex]\[
\begin{array}{l}
(r \circ q)(7) = \\
(q \circ r)(7) =
\end{array}
\][/tex]

[tex]\[\square\][/tex]
[tex]\[\square\][/tex]


Sagot :

Sure, let's solve this step by step.

### Finding [tex]\((r \circ q)(7)\)[/tex]
The notation [tex]\((r \circ q)(7)\)[/tex] means we first apply the function [tex]\(q\)[/tex] to the number 7, and then apply the function [tex]\(r\)[/tex] to the result from [tex]\(q\)[/tex].

1. First, calculate [tex]\(q(7)\)[/tex]:
[tex]\[ q(x) = x^2 + 6 \][/tex]
Substituting [tex]\(x = 7\)[/tex]:
[tex]\[ q(7) = 7^2 + 6 = 49 + 6 = 55 \][/tex]

2. Next, use this result to find [tex]\(r(q(7))\)[/tex] which is [tex]\(r(55)\)[/tex]:
[tex]\[ r(x) = \sqrt{x + 9} \][/tex]
Substituting [tex]\(x = 55\)[/tex]:
[tex]\[ r(55) = \sqrt{55 + 9} = \sqrt{64} = 8 \][/tex]

Thus, [tex]\((r \circ q)(7) = 8.0\)[/tex].

### Finding [tex]\((q \circ r)(7)\)[/tex]
The notation [tex]\((q \circ r)(7)\)[/tex] means we first apply the function [tex]\(r\)[/tex] to the number 7, and then apply the function [tex]\(q\)[/tex] to the result from [tex]\(r\)[/tex].

1. First, calculate [tex]\(r(7)\)[/tex]:
[tex]\[ r(x) = \sqrt{x + 9} \][/tex]
Substituting [tex]\(x = 7\)[/tex]:
[tex]\[ r(7) = \sqrt{7 + 9} = \sqrt{16} = 4 \][/tex]

2. Next, use this result to find [tex]\(q(r(7))\)[/tex] which is [tex]\(q(4)\)[/tex]:
[tex]\[ q(x) = x^2 + 6 \][/tex]
Substituting [tex]\(x = 4\)[/tex]:
[tex]\[ q(4) = 4^2 + 6 = 16 + 6 = 22 \][/tex]

Thus, [tex]\((q \circ r)(7) = 22.0\)[/tex].

To summarize:
[tex]\[ (r \circ q)(7) = 8.0 \][/tex]
[tex]\[ (q \circ r)(7) = 22.0 \][/tex]