Question

Given that f(x) = x2 + 10x + 21 and g(x) = x + 7, find (f•g)(x) and express

Answer 1

Answer:

$(f.g)x = {x}^{2} + 24x + 140$

Step-by-step explanation:

$given \\ f(x) = x ^{2} + 10x + 21 \: and \: g(x) = x + 7$

$as \: we \: know \: (f.g)x \: is \: same \: as$

$f(g(x))$

$so \:$

$f(x + 7) = ( x + 7) ^{2} + 10(x + 7) + 21$

$f(x + 7) = {x}^{2} + 14x + 49 + 10x + 70 + 21$

$f(x + 7) = x^{2} + 24x + 140$

$therefore$

$(f.g)x = {x}^{2} + 24x + 140$