2 câu trả lời
Đáp án:
•$(\frac{4}{15}+\frac{7}{12}-\frac{19}{20}).\frac{5}{2}+\frac{1}{4}$ =0
•$24.(\frac{-1}{5})^{3}+\frac{1}{5}-2.(\frac{-1}{2})^2-\frac{1}{2}$=$\frac{-124}{125}$
Giải thích các bước giải:
$(\frac{4}{15}+\frac{7}{12}-\frac{19}{20}).\frac{5}{2}+\frac{1}{4}$
=$(\frac{4×4+7×5-19×3}{60}).\frac{5}{2}+\frac{1}{4}$
=$(\frac{16+35-57}{60}).\frac{5}{2}+\frac{1}{4}$
=$\frac{-6}{60}.\frac{5}{2}+\frac{1}{4}$
=$\frac{-1}{10}.\frac{5}{2}+\frac{1}{4}$
=$\frac{-1}{4}$+$\frac{1}{4}$
=0
$24.(\frac{-1}{5})^{3}+\frac{1}{5}-2.(\frac{-1}{2})^2-\frac{1}{2}$
=$24.(\frac{-1}{125})+\frac{1}{5}-2.\frac{1}{4}-\frac{1}{2}$
=$\frac{-24}{125}+\frac{1}{5}-\frac{1}{2}-\frac{1}{2}$
=$\frac{-24}{125}+\frac{1}{5}-1$
=$\frac{-24}{125}+\frac{1}{5}-\frac{5}{5}$
=$\frac{-24}{125}-\frac{4}{5}$
=$\frac{-24}{125}-\frac{100}{125}$
=$\frac{-124}{125}$
Bạn tham khảo nhé
($\frac{4}{15}$ + $\frac{7}{12}$ - $\frac{19}{20}$) x $\frac{5}{2}$ + $\frac{1}{4}$
= (-$\frac{1}{10}$) x $\frac{5}{2}$ + $\frac{1}{4}$
= (-$\frac{1}{4}$) + $\frac{1}{4}$
= 0
Vậy ($\frac{4}{15}$ + $\frac{7}{12}$ - $\frac{19}{20}$) x $\frac{5}{2}$ + $\frac{1}{4}$ = 0
24 x (-$\frac{1}{5}$)³ + $\frac{1}{5}$ - 2 x (-$\frac{1}{2}$)² - $\frac{1}{2}$
= 24 x (-$\frac{1}{125}$) + $\frac{1}{5}$ - 2 x $\frac{1}{4}$ - $\frac{1}{2}$
= (-$\frac{24}{125}$) + $\frac{1}{5}$ - $\frac{1}{2}$ - $\frac{1}{2}$
= $\frac{1}{125}$ - $\frac{1}{2}$ - $\frac{1}{2}$
= (-$\frac{123}{250}$) - $\frac{1}{2}$
= -$\frac{124}{125}$
Vậy 24 x (-$\frac{1}{5}$)³ + $\frac{1}{5}$ - 2 x (-$\frac{1}{2}$)² - $\frac{1}{2}$ = -$\frac{124}{125}$
