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\(\frac{74\times158+69}{158\times75-89}\)
= \(\frac{74\times158+69}{158\times\left(74+1\right)-89}\)
= \(\frac{74\times158+69}{158\times74+158-89}\)
= \(\frac{74\times158+69}{158\times74+\left(158-89\right)}\)
= \(\frac{74\times158+69}{74\times158+69}\)
= 1
a) =\(\left[\left(12+1\right)^2+\left(12+2\right)^2\right]:\left(13^2+14^2\right)\)
=1
b)=(1.2.3....8).(9-1-8)
=(1.2.3....8).0
=0
mik chỉ giải được zậy thôi.
t mik nha.
Bài làm:
Ta có:
\(B=-66\cdot\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
\(B=\left(-66\right).\frac{1}{2}+66.\frac{1}{3}-66.\frac{1}{11}-124.\left(37+63\right)\)
\(B=-33+22-6-124.100\)
\(B=17-12400\)
\(B=-12383\)
\(B=-66.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{11}\right)+124.\left(-37\right)+63.\left(-124\right)\)
\(=-66.\frac{1}{2}-\left(-66\right).\frac{1}{3}+\left(-66\right).\frac{1}{11}+\left(-124\right).37+63.\left(-124\right)\)
\(=-33+22-6+\left(-124\right).\left(37+63\right)\)
\(=-11-6+\left(-124\right).100\)
\(=-17-12400\)
\(=-12417\)
\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
\(=\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{2}{6}-\frac{2}{8}+\frac{2}{10}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\frac{2.\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7.\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}-\frac{2.\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}{7.\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}\)
\(=\frac{2}{7}-\frac{2}{7}\)
\(=0\)
\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}=\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\frac{2\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}\)
\(=\frac{2}{7}-\frac{1}{\frac{7}{2}}\)
\(=\frac{2}{7}-\frac{2}{7}=0\)
Study well ! >_<
a) 3784 + 23 – 3785 – 15
= 3784 - 3785 + 23 - 15
= -(3785 - 3784) + 8
= -1 + 8
= 8 - 1
= 7
b) 21 + 22 + 23 + 24 – 11 - 12 - 13 - 14
= (21 -11) + (22 - 12) + (23 - 13) + (24 - 14)
= 10 + 10 + 10 + 10
= 40
Sách Giáo Khoa
Bài giải:
a)
3784 + 23 - 3785 - 15 . Áp dụng tính chất giao hoán ta có:
= (3784 - 3785) + (23 - 15)
= -1 + 8
= 7
b) 21 + 22 + 23 + 24 - 11 - 12 - 13 - 14. Áp dụng các tính chất giao hoán và kết hợp ta có:
= (21 - 11) + (22 - 12) + (23 - 13) + (24 - 14).
= 10 + 10 + 10 + 10
= 40
Đáp số: a) 7; b) 40.
Ta phá ngoặc
\(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)=11\frac{3}{13}-5\frac{3}{13}-2\frac{4}{7}=6-2\frac{4}{7}=3\frac{3}{7}\)
11mũ2 . (25+75)-2200
11mũ2 . 100 -2200
121 . 100 -2200
12100 -2200
9900
\(11^2\)x(25+75)-2200
=\(11^2\) x 100 -2200
=121 x 100 -2200
=12100 - 2200
=9900
Chúc e học tốt nhee