Question

3)Dadas as funções reais definidas por f(x)= x.(3x + 4) e g(x)= x2 + 2x – 1, calcule: a)f(4)=
b)g(5)=
c)f(7)=
d)g(10)=

Answer 1

Resposta:

a)f(4)=64                  c)f(7)=175

b)g(5)=34                 d)g(10)=119

Explicação passo a passo:

Para cada questão, você substitui o x para  valor fornecido dentro dos parênteses em f(x) ou g(x).

a)f(4)

x=4

$\mathsf{f(x)=x\cdot (3x+4)}\\\\\mathsf{f(4)=4\cdot (3\cdot4 + 4)}\\\\\mathsf{f(4)=4\cdot(12+4)}\\\\\mathsf{f(4)=4\cdot 16}\\\\\boxed{\mathsf{f(4)=64}}$

b)g(5)

x=5

$\mathsf{g(x)=x^{2}+2x-1}\\\\\mathsf{g(5)=5^{2}+2\cdot 5 -1}\\\\\mathsf{g(5)=25+10-1}\\\\\boxed{\mathsf{g(5)=34}}$

c)f(7)

x=7

$\mathsf{f(x)=x\cdot (3x+4)}\\\\\mathsf{f(7)=7\cdot (3\cdot7+4)}\\\\\mathsf{f(7)=7\cdot (21+4)}\\\\\mathsf{f(7)=7\cdot 25}\\\\\boxed{\mathsf{f(7)=175}}$

d)g(10)

x=10

$\mathsf{g(x)=x^{2}+2x-1}\\\\\mathsf{g(10)=10^{2}+2\cdot 10-1}\\\\\mathsf{g(10)=100+20-1}\\\\\boxed{\mathsf{g(10)=119}}$