Question

A função f (x)=3/5 x -1 e g (x)=4/3 x + 4 DETERMINE: A) f (3) +3 g (1/3) B) f (1/4) - 2 g (5/2)

Me ajudem resolver está questão!

Answer 1

Para resolver basta substituir x pelo valor fornecido.
$f(x)= \frac{3}{5}.x -1 \\ \\ g(x)= \frac{4}{3}.x+4 \\ \\ a) f(3)+3.g( \frac{1}{3}) \\ \\ f(x)= \frac{3}{5}.x -1 \\ \\ f(3)= \frac{3}{5}.3 -1 = \frac{9-5}{5} = \frac{4}{5} \\ \\ g(x)= \frac{4}{3}.x+4 \\ \\ g( \frac{1}{3})= \frac{4}{3}. \frac{1}{3}+4= \frac{4+36}{9} = \frac{40}{9} \\ \\ f(3)+3.g( \frac{1}{3}) =\frac{4}{5}+3.\frac{40}{9}=\frac{4}{5}+\frac{40}{3}= \frac{12+200}{15} = \frac{212}{15}$
$b) f( \frac{1}{4} )-2.g( \frac{5}{2} ) \\ \\ f(x)= \frac{3}{5}.x -1 \\ \\ f( \frac{1}{4})= \frac{3}{5}. \frac{1}{4} -1 = \frac{3-20}{20} =- \frac{17}{20} \\ \\ g(x)= \frac{4}{3}.x+4 \\ \\ g(\frac{5}{2})= \frac{4}{3}.\frac{5}{2}+4 =\frac{2}{3}.\frac{5}{1}+4= \frac{10+12}{3} = \frac{22}{3} \\ \\ f( \frac{1}{4} )-2.g( \frac{5}{2}) =- \frac{17}{20}-2. \frac{22}{3} = \frac{-51-880}{60}= -\frac{931}{60}$

Respostas:
$a) \\ \\ \frac{212}{15} \\ \\ b) \\ \\ -\frac{931}{60}$