2+3×(2×4)=0,4
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a) = 0,16 - 0,064 . (-3)
= 0,16 + 0,192
= 0,352
b) = (7/4)³ - (7/4)² + 1
= 343/64 - 49/16 + 1
= 147/64 + 1
= 211/64
c) = 8/27 - 4.(-7/4)² - 8/27
= -4.49/16
= -49/4
Lời giải:
a. $=0,16-(-0,064).(-3)=0,16-0,192=-0,032$
b. $=(1\frac{3}{4})^2(1\frac{3}{4}-1)+1=(1\frac{3}{4})^2.\frac{3}{4}+1$
$=\frac{147}{64}+1=\frac{211}{64}$
c.
$=(\frac{2}{3})^3-4(\frac{-7}{4})^2-(\frac{2}{3})^3$
$=-4(\frac{-7}{4})^2=\frac{-49}{4}$
\(A=\dfrac{2}{3}+\dfrac{3}{4}.\left(\dfrac{-4}{9}\right)\)
\(A=\dfrac{2}{3}+\dfrac{-1}{3}\)
\(A=\dfrac{1}{3}\)
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( *Xem lại câu B nha bạn )
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\(C=\left(\dfrac{3}{4}-0,2\right).\left(0,4-\dfrac{4}{5}\right)\)
\(C=\left(\dfrac{3}{4}-\dfrac{1}{5}\right).\left(\dfrac{2}{5}-\dfrac{4}{5}\right)\)
\(C=\dfrac{11}{20}.\dfrac{-2}{5}\)
\(C=\dfrac{-11}{50}\)
\(c,2\dfrac{1}{2}.\left(\dfrac{5}{2}-30\%\right)+2\\ =\dfrac{5}{2}.\left(\dfrac{5}{2}-\dfrac{3}{10}\right)+2\\ =\dfrac{5}{2}.\left(\dfrac{5.5-3}{10}\right)+2\\ =\dfrac{5}{2}.\dfrac{11}{5}+2\\ =\dfrac{11}{2}+2\\ =\dfrac{11+2.2}{2}\\ =\dfrac{15}{2}\)
\(d,3\dfrac{1}{2}-0,4.\left(50\%-\dfrac{3}{2}\right)+\dfrac{3}{4}\\ =\dfrac{7}{2}-\dfrac{2}{5}.\left(\dfrac{1}{2}-\dfrac{3}{2}\right)+\dfrac{3}{4}\\ =\dfrac{7}{2}-\dfrac{2}{5}.\left(\dfrac{-2}{2}\right)+\dfrac{3}{4}\\ =\dfrac{7}{2}-\dfrac{2}{5}.\left(-1\right)+\dfrac{3}{4}\\ =\dfrac{7}{2}+\dfrac{2}{5}+\dfrac{3}{4}\\ =\dfrac{70}{20}+\dfrac{8}{20}+\dfrac{15}{20}\\ =\dfrac{93}{20}\)
\(-2\dfrac{3}{4}.\left(-0,4\right)+1\dfrac{2}{5}.2,75-\left(-1,2\right):\dfrac{4}{11}\)
\(=\dfrac{11}{4}.\dfrac{2}{5}+\dfrac{7}{5}.\dfrac{11}{4}+\dfrac{6}{5}.\dfrac{11}{4}\)
\(=\dfrac{11}{4}.\left(\dfrac{2}{5}+\dfrac{7}{5}+\dfrac{6}{5}\right)\)
\(=\dfrac{11}{4}.\dfrac{15}{5}\)
\(=\dfrac{11}{4}.3\)
\(=\dfrac{33}{4}\)
\(c`3,4.0,7+3,4.0,3-0,4=3,4.\left(0,7+0,3\right)-0,4=3,4.10-0,4=34-0,4=33,6\)
\(d`\left(1-\dfrac{1}{2}+\dfrac{3}{4}\right)-\left(\dfrac{1}{2}+1\dfrac{3}{4}-3\right)=\left(1-\dfrac{1}{2}+\dfrac{3}{4}\right)-\left(\dfrac{1}{2}+\dfrac{7}{4}-3\right)=1-\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{1}{2}-\dfrac{7}{4}+3=\left(1+3\right)+\left(-\dfrac{1}{2}-\dfrac{1}{2}\right)+\left(\dfrac{3}{4}-\dfrac{7}{4}\right)=4+\left(-1\right)+\left(-1\right)=2\)
\(\left(1+2+3+4+5+6+...+999+1000\right)\times\left(0.75\times0.4-\dfrac{3}{4}\times0.3\right)\)
\(=\dfrac{\left(1000+1\right)\times1000}{2}\times\left[0.75\times\left(0.4-0.3\right)\right]\)
\(=500500\times0.75\times0.1=375375\)
Giải:
\(\left(1+2+3+4+5+6+...+999+1000\right).\left(0,75.0,4-\dfrac{3}{4}.0,3\right)\)
Số số hạng \(\left(1+2+3+4+5+6+...+999+1000\right)\) là:
\(\left(1000-1\right):1+1=1000\)
Tổng dãy \(\left(1+2+3+4+5+6+...+999+1000\right)\) là:
\(\left(1+1000\right).1000:2=500500\)
\(\Rightarrow\left(1+2+3+4+5+6+...+999+1000\right).\left(0,75.0,4-\dfrac{3}{4}.0,3\right)\)
\(=500500.\left[0,75.\left(0,4-0,3\right)\right]\)
\(=500500.\left[0,75.0,1\right]\)
\(=500500.0,075\)
\(=37537,5\)
Đề sai rùi , bn ktra lại nhen
`2+3.(2.4)=0,4`
Đề là tìm `x` thì có thiếu đề ko v bn ?