Câu 1: Thực hiên phép tính:
a,24- { 12 – [ (-10)-(-2)]}
b,2/3 + 1/3 . ( -2/3 + 5/6 ) : 2/3
Câu2 : tinh nhanh
a, 2/5 + ( 5/9+2/5)
b,17/13 – (4/13-11)
c,3/5.18/17+3/5.9/17-3/5.10/17
Câu 1: Thực hiên phép tính:
a,24- { 12 – [ (-10)-(-2)]}
b,2/3 + 1/3 . ( -2/3 + 5/6 ) : 2/3
Câu2 : tinh nhanh
a, 2/5 + ( 5/9+2/5)
b,17/13 – (4/13-11)
c,3/5.18/17+3/5.9/17-3/5.10/17
Đáp án:
Tham khảo
Giải thích các bước giải:
Câu 1 :
a) 24 – { 12 – [ (-10) – (-2)]}
= 24 – { 12 – [ -10 + 2 ]}
= 24 – { 12 – [-8]}
= 24 – ( 12 + 8 )
= 24 – 20
= 4
b) $\frac{2}{3}$ + $\frac{1}{3}$ . ($\frac{-2}{3}$ + $\frac{5}{6}$ ) : $\frac{2}{3}$
= $\frac{2}{3}$ + $\frac{1}{3}$ . ( $\frac{-4}{6}$ + $\frac{5}{6}$ ) . $\frac{3}{2}$
= $\frac{2}{3}$ + $\frac{1}{3}$ . $\frac{1}{6}$ . $\frac{3}{2}$
= $\frac{2}{3}$ + $\frac{1}{18}$ . $\frac{3}{2}$
= $\frac{2}{3}$ + $\frac{1}{12}$
= $\frac{3}{4}$
Câu 2 :
a) $\frac{2}{5}$ + ( $\frac{5}{9}$ + $\frac{2}{5}$ )
= $\frac{2}{5}$ + $\frac{5}{9}$ + $\frac{2}{5}$
= $\frac{2}{5}$ + $\frac{2}{5}$ + $\frac{5}{9}$
= $\frac{4}{5}$ + $\frac{5}{9}$
= $\frac{61}{45}$
b) $\frac{17}{13}$ – ( $\frac{4}{13}$ – 11 )
= $\frac{17}{13}$ – $\frac{4}{13}$ + 11
= $\frac{13}{13}$ + 11
= 1 + 11
= 12
c) $\frac{3}{5}$ . $\frac{18}{17}$ + $\frac{3}{5}$ . $\frac{9}{17}$ – $\frac{3}{5}$ . $\frac{10}{17}$
= $\frac{3}{5}$ . ( $\frac{18}{17}$ + $\frac{9}{17}$ – $\frac{10}{17}$ )
= $\frac{3}{5}$ . $\frac{17}{17}$
= $\frac{3}{5}$ . 1
= $\frac{3}{5}$