Step 1 :
\Given functions
\f(x) = 3x − 12
\g(x) = 2x2 + 7x − 11
\gof(x) = g [ f(x) ]
\g [ 3x − 12 ]
\2( 3x − 12 )2 + 7 ( 3x − 12 ) − 11
\Apply formula : (a+b)2=a2+2ab+b2
\2[ (3x)2 - 2(3x)(12) + (12)2 ] + 21x − 84 − 11
\2[ 9x2 - 72x + 144 ] + 21x − 84 − 11
\18x2 - 144x + 288 + 21x − 84 − 11
\18x2 - 123x + 193
\So (gof)(x) = 18x2 - 123x + 193
\Step 2 :
\(gof)(x) = 18x2 - 123x + 193
\Substitute x = 4
\(gof)(4) = 18(4)2 - 123(4) + 193
\(gof)(4) = -11
\Solution :
\The solutio is (gof)(4) = -11
\