Question

Dada a função do 1º grau f(x) = 1 – 5x, determine:

a) f(0)
b) f(-1)
c) f(1/5)
d) f(-1/5)
e) f(8)
f) f(10)
g) f(12)

Answer 1

$\text{f}(x)=1-5x$

a) $\text{f}(0)=1-5\cdot0=1-0=1 \iff \boxed{\text{f}(0)=1}$

b) $\text{f}(-1)=1-5\cdot(-1)=1+5=6 \iff \boxed{\text{f}(-1)=6}$

c) $\text{f}\left(\dfrac{1}{5}\right)=\dfrac{1}{5}-5\cdot\dfrac{1}{5}=\dfrac{1}{5}-1=\dfrac{1-5}{5}=-\dfrac{4}{5} \iff \boxed{\text{f}\left(\dfrac{1}{5}\right)=-\dfrac{4}{5}}$

d) $\text{f}\left(-\dfrac{1}{5}\right)=-\dfrac{1}{5}-5\cdot\left(-\dfrac{1}{5}\right)=-\dfrac{1}{5}+1=\dfrac{-1+5}{5}=\dfrac{4}{5} \iff \boxed{\text{f}\left(-\dfrac{1}{5}\right)=\dfrac{4}{5}}$

e) $\text{f}(8)=1-5\cdot8=1-40=-39 \iff \boxed{\text{f}(8)=-39}$

f) $\text{f}(10)=1-5\cdot10=1-50=-49 \iff \boxed{\text{f}(10)=-49}$

g) $\text{f}(12)=1-5\cdot12=1-60=-59 \iff \boxed{\text{f}(12)=-59}$