Question

Найдите значение выражения 3а-7/2а+5 при а= -2; -0,4; 0; 2,5;

Answer 1

$\frac{3a-7}{2a+5} \\ \\ 1) a=-2 \\ \\ \frac{3*(-2) -7}{2*(-2)+5} = \frac{-6-7}{-4+5} = \frac{-13}{1} = -13 \\ \\ 2)a=-0.4 \\ \\ \frac{3*(-0.4)-7}{2*(-0.4)+5}= \frac{-1.2-7}{-0.8+5} = \frac{-8.2}{4.2} = - \frac{82}{42} =- \frac{41}{21} =- 1 \frac{20}{21} \\ \\ 3)a=0 \\ \\ \frac{3*0-7}{2*0+5} = \frac{-7}{5} = - 1.4 \\ \\ 4)a=2.5 \\ \\ \frac{3*2.5-7}{2*2.5+5}= \frac{7.5 - 7}{5 + 5} = \frac{0.5}{10} = 0.05$