Tính :
\(A=-66.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
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C=\(-66.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63\left(-124\right)\)
C=-66.(1/2-1/3+1/11)+124.(-37)+63.(-124)
C=-66.17/66-124.(37+63)
C=-17-124.100
C=-12417
Bài làm:
Ta có:
\(B=-66\cdot\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
\(B=\left(-66\right).\frac{1}{2}+66.\frac{1}{3}-66.\frac{1}{11}-124.\left(37+63\right)\)
\(B=-33+22-6-124.100\)
\(B=17-12400\)
\(B=-12383\)
\(B=-66.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
\(=-66.\frac{1}{2}-\left(-66\right).\frac{1}{3}+\left(-66\right).\frac{1}{11}+\left(-124\right).37+63.\left(-124\right)\)
\(=-33+22-6+\left(-124\right).\left(37+63\right)\)
\(=-11-6+\left(-124\right).100\)
\(=-17-12400\)
\(=-12417\)
1, \(B=\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)...........\left(1-\dfrac{1}{n+1}\right)\)
\(=\left(\dfrac{2}{2}-\dfrac{1}{2}\right)\left(\dfrac{3}{3}-\dfrac{1}{3}\right)...........\left(\dfrac{n+1}{n+1}-\dfrac{1}{n+1}\right)\)
\(=\dfrac{1}{2}.\dfrac{2}{3}..............\dfrac{n}{n+1}\)
\(=\dfrac{1.2.3........n}{2.3.......\left(n+1\right)}\)
\(=\dfrac{1}{n+1}\)
2, \(A=\dfrac{1}{1.2}+\dfrac{1}{2.3}+...........+\dfrac{1}{99.100}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+............+\dfrac{1}{99}-\dfrac{1}{100}\)
\(=1-\dfrac{1}{100}\)
\(=\dfrac{99}{100}\)
C=\(-66\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
=\(-66.\left(\dfrac{5}{66}\right)+124\left(-37-63\right)=-5+124.\left(-100\right)\)
=-12405
\(-66\cdot\left[\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right]+124\cdot\left[-37\right]+63\cdot\left[-1+24\right]\)
\(=-66\cdot\left[\frac{1}{6}+\frac{1}{11}\right]+\left[-4588\right]+63\cdot23\)
\(=-66\cdot\frac{17}{66}+\left[-4588\right]+1449\)
\(=-17+\left[-4588\right]+1449=-4605+1449=-3156\)
Các bạn ủng hộ cho mình nhé
\(A=-66.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
\(A=-66.\left(\frac{33}{66}-\frac{22}{66}+\frac{6}{66}\right)+\left(-124\right).\left(37+63\right)\)
\(A=-66.\frac{17}{66}+\left(-124\right).100\)
\(A=-17+\left(-12400\right)\)
A = -12417
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