Đáp án + Giải thích các bước giải:
b) $\frac{5x}{4}+(\frac{-1}{2})^2=\frac{3}{4}-\frac{7}{3}$
$⇒\frac{3.5x}{12}+\frac{3.(-1)^2}{12}=\frac{3.3}{12}-\frac{4.7}{12}$
$⇒\frac{15x+3}{12}=\frac{-19}{12}$
$⇒-19.12=12(15x+3)$
$⇒-228=180x+36$
$⇒-264=180x$
$⇒x=\frac{-22}{15}$
Vậy $x=\frac{-22}{15}$
c) $-1\frac{2}{5}y=0,4$
$⇒\frac{-7}{5}y=0,4$
$⇒y=0,4:\frac{-7}{5}$
$⇒y=\frac{-2}{7}$
Vậy $y=\frac{-2}{7}$
d) $\text{25 % x + }$$ \frac{1}{4}=\frac{3}{5}$
$⇒0,25x+\frac{1}{4}=\frac{3}{5}$
$⇒\frac{0,25x.20}{20}+\frac{1.5}{20}=\frac{3.4}{20}$
$⇒\frac{5x+5}{20}=\frac{12}{20}$
$⇒12.20=20(5x+5)$
$⇒240=100x+100$
$⇒140=100x$
$⇒x=1,4$
Vậy $x=1,4$
