Question

seja uma função f definida por f(x) = 4x-21,determine f(12) + f(1) e f(3) * f(5)


por favor me ajudem ​

Answer 1

Resposta:

f(12) + f(1) = 10

f(2) x f(5)= 9

Explicação passo-a-passo:

f(12)= 4 x 12 -21= 27

f(1)= 4 x 1 -21= -17

f(3)= 4 x 3 -21= -9

f(5)= 4 x 5 -21= -1

f(12) + f(1) = 27 +(-17) = 10

f(2) x f(5)= -9 x (-1)= 9

Answer 2

f (12)

$f(x) \ = \ 4x \ - \ 21 \\\\f(12) \ \ = \ \ 4 \ . \ 12 \ - \ 21 \\\\ f(12) \ \ = \ \ 48 \ - \ 21 \\\\ \boxed{ \ f(12) \ \ = \ \ 27 \ }$

f(1)

$f(x) \ \ = \ \ 4x \ - \ 21 \\\\ f(1) \ \ = \ \ 4 \ . \ 1 \ - \ 21 \\\\ f(1) \ \ = \ \ 4 \ - \ 21 \\\\ \boxed{ \ f(1) \ \ = \ \ -17 \ }$

f (3)

$f(x) \ \ = \ \ 4x \ - \ 21 \\\\ f(3) \ \ = \ \ 4 \ . \ 3 \ - \ 21 \\\\ f(3) \ \ = \ \ 12 \ - \ 21 \\\\ \boxed{ \ f(3) \ \ = \ \ -9 \ }$

f (5)

$f(x) \ \ = \ \ 4x \ - \ 21 \\\\ f(5) \ \ = \ \ 4 \ . \ 5 \ - \ 21 \\\\ f(5) \ \ = \ \ 20 \ - \ 21 \\\\ \boxed{ \ f(5) \ \ = \ \ -1 \ }$

f(12)  +  f(1)

$27 \ + \ (-17) \ \ \ \Rightarrow \ \ \ 27 \ - \ 17 \ \ \ \Rightarrow \ \ \boxed{\boxed{ \ 10 \ }}$

f(3)  ×  f(5)

$(-9) \ \times \ (-1) \ \ \ \Rightarrow \ \ \ \boxed{\boxed{ \ 9 \ }}$