Find x Such That g(f(x))=8

Find the Values of \( x \) Such That \( g(f(x))=8 \)

Question:

If

\[ f(x)=2x+3 \]

and

\[ g(x)=x^2+7 \]

then the values of \(x\) such that

\[ g(f(x))=8 \]

are

(a) \(1,2\)
(b) \(-1,2\)
(c) \(-1,-2\)
(d) \(1,-2\)

Solution:

\[ g(f(x))=(2x+3)^2+7 \]

Given,

\[ (2x+3)^2+7=8 \]

\[ (2x+3)^2=1 \]

\[ 2x+3=\pm1 \]

If

\[ 2x+3=1 \]

\[ x=-1 \]

If

\[ 2x+3=-1 \]

\[ x=-2 \]

Therefore,

\[ \boxed{\text{Correct Answer: (c)}} \]

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