Bài 2:
a) $\frac{-7}{25}$ . $\frac{11}{13}$ + $\frac{-7}{25}$ . $\frac{2}{13}$ - $\frac{18}{25}$
= $\frac{-7}{25}$ . ($\frac{11}{13}$ + $\frac{2}{13}$ ) - $\frac{18}{25}$
= $\frac{-7}{25}$ . 1 - $\frac{18}{25}$
= $\frac{-7}{25}$ - $\frac{18}{25}$ = $\frac{-25}{25}$ = -1
b) ($\frac{3}{4}$ + $\frac{-7}{2}$ ) . ( $\frac{10}{11}$ + $\frac{2}{22}$ )
= ($\frac{3 + ( - 14)}{4}$ ) . ( $\frac{20+ 2}{22}$ )
= $\frac{-11}{4}$ . $\frac{22}{22}$
= $\frac{-11}{4}$ . 1 = $\frac{-11}{4}$
c) $\frac{1}{7}$ - $\frac{8}{7}$ : 8 - 3 : $\frac{3}{4}$ . (-2)$^{2}$
= $\frac{1}{7}$ - $\frac{8}{7}$ . $\frac{1}{8}$ - 3 . $\frac{4}{3}$ . 4
= $\frac{1}{7}$ - $\frac{1}{7}$ - 16
= 0 - 16 = -16
Bài 3:
a) $\frac{1}{2}$x + $\frac{1}{2}$ = $\frac{5}{2}$
$\frac{1}{2}$x = $\frac{5}{2}$ - $\frac{1}{2}$
$\frac{1}{2}$x = $\frac{4}{2}$ = 2
x = 2 : $\frac{1}{2}$ = 2 . 2
x = 4
b) $\frac{-2}{3}$ - $\frac{1}{3}$(2x - 5) = $\frac{3}{2}$
$\frac{1}{3}$(2x - 5) = $\frac{-2}{3}$ - $\frac{3}{2}$
$\frac{1}{3}$(2x - 5)= $\frac{-5}{2}$
2x - 5= $\frac{-5}{2}$ : $\frac{1}{3}$ = $\frac{-5}{2}$ . 3
2x - 5= $\frac{-15}{2}$
2x = $\frac{-15}{2}$ + 5= $\frac{-15}{2}$ + $\frac{10}{2}$
2x = $\frac{-5}{2}$
x = $\frac{-5}{2}$ : 2= $\frac{-5}{2}$ . $\frac{1}{2}$
x = $\frac{-10}{4}$
cho mik xin 5*và ctlhn
@chúc bn hok tốt
