Question

questão de matemática

f(x)= x2 - 4x + 7

A) 56
B) 4
C) 53
D) 13

​

Answer 1

$\Large\displaystyle{}f\left(x\right) = {x}^{2} - 4x + 7$

Vamos lá:

A)

$\Large\displaystyle{}f\left(56\right) = {56}^{2} - 4 \times 56 + 7 \\ \Large\displaystyle{}f\left(56\right) = 3136 - 4 \times 56 + 7 \\ \Large\displaystyle{}f\left(56\right) = 3136 - 224 + 7 \\ \Large\displaystyle{}f\left(56\right) = 2912 + 7 \\ \Large\displaystyle{}f\left(56\right) = 2919$

B)

$\Large\displaystyle{}f\left(4\right) = {4}^{2} - 4 \times 4 + 7 \\ \Large\displaystyle{}f\left(4\right) = 16 - 4 \times 4 + 7 \\ \Large\displaystyle{}f\left(4\right) = 16 - 16 + 7 \\ \Large\displaystyle{}f\left(4\right) = 0 + 7 \\ \Large\displaystyle{}f\left(4\right) = 7$

C)

$\Large\displaystyle{}f\left(53\right) = {53}^{2} - 4 \times 53 + 7 \\ \Large\displaystyle{}f\left(53\right) = 2809 - 4 \times 53 + 7 \\ \Large\displaystyle{}f\left(53\right) = 2809 - 212 + 7 \\ \Large\displaystyle{}f\left(53\right) = 2597 + 7 \\ \Large\displaystyle{}f\left(53\right) = 2604$

D)

$\Large\displaystyle{}f\left(13\right) = {13}^{2} - 4 \times 13 + 7 \\ \Large\displaystyle{}f\left(13\right) = 169 - 4 \times 13 + 7 \\ \Large\displaystyle{}f\left(13\right) = 169 - 52 + 7 \\ \Large\displaystyle{}f\left(13\right) = 117 + 7 \\ \Large\displaystyle{}f\left(13\right) = 124$

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