a) $\frac{3}{5}$ + $\frac{(-2)}{5}$
= $\frac{1}{5}$
b) $\frac{-11}{7}$ . $\frac{3}{17}$ + $\frac{4}{7}$ . $\frac{3}{17}$
= $\frac{3}{17}$ . ($\frac{(-11)}{7}$ + $\frac{4}{7}$)
= $\frac{3}{17}$ . (-1)
= $\frac{-3}{17}$
c) 2³ - 8 . 3 + 0,5 . 25%
= 8 - 24 + 0,125
= -15.875
d) 3$\frac{1}{2}$ + 0,8 + $\frac{3}{5}$
= 3,5 + 0,8 + 0,6
= 4,9
Câu 2 :
a) $\frac{2}{7}$ . x = $\frac{-1}{6}$
x = $\frac{-1}{6}$ : $\frac{2}{7}$
x = $\frac{-12}{7}$
b) $\frac{2}{3}$ . (x + 1) + $\frac{3}{4}$ = $\frac{7}{12}$
$\frac{2}{3}$ . (x + 1) = $\frac{7}{12}$ - $\frac{3}{4}$
$\frac{2}{3}$ . (x + 1) = $\frac{-1}{6}$
x + 1 = $\frac{-1}{6}$ : $\frac{2}{3}$
x + 1 = $\frac{-1}{4}$
x = $\frac{-1}{4}$ - 1
x = $\frac{5}{4}$
c) |x+2| = 5
TH 1 : x + 2 = 5
x = 5 - 2
x = 3
TH 1 : x + 2 = -5
x = 5 + 2
x = 7
Vậy x = {3;7}
#ht
*Xin ctlhn
