4^5 nhân 9^4 - 2 nhân 6^9
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2^10 nhân 3^8 + 6^8 nhân 20
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\(a=4^5.9^4-2.\dfrac{6^9}{2^{10}}.3^8+6^8.20\)
Đề là như vầy đúng ko bn?
( 45 - 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= ( 45 - 45 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0
( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 ) x ( 72 - 8 x 8 - 8 )
= ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 ) x ( 72 - 64 - 8 )
= ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 ) x 0
= 0
a) \(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}\)
\(=1-\frac{1}{4}\)
\(=\frac{3}{4}\)
b) \(\frac{4}{7}\times\frac{8}{9}+\frac{4}{7}\times\frac{1}{9}\)
\(=\frac{4}{7}\times\left(\frac{8}{9}+\frac{1}{9}\right)\)
\(=\frac{4}{7}\times1\)
\(=\frac{4}{7}\)
c) \(\frac{13}{6}\times\frac{3}{8}-\frac{3}{8}\times\frac{7}{6}\)
\(=\frac{3}{8}\times\left(\frac{13}{6}-\frac{7}{6}\right)\)
\(=\frac{3}{8}\times1\)
\(=\frac{3}{8}\)
d) \(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+...+\frac{1}{9x10}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\)
\(=1-\frac{1}{10}\)
\(=\frac{9}{10}\)
\(a,\)\(\frac{2^5\times3^{12}\times7^8}{2^7\times3^{10}\times7^9}=\frac{3^2\times\left(2^5\times3^{10}\times7^8\right)}{2^2\times7\times\left(2^5\times3^{10}\times7^8\right)}\)\(=\frac{3^2}{2^2\times7}=\frac{9}{28}\)
\(b,\)Tương tự
\(\dfrac{4^{^5}.9^{^4}-2.6^{^9}}{2^{^{10}}.3^{^8}+6^{^8}.20}\)=\(\dfrac{2^{^{10}}.3^{^8}-2.2^{^9}.3^{^9}}{2^{^{10}}.3^{^8}+2^{^8}.3^{^8}.2^{^2}.5}\)=\(\dfrac{2^{^{10}}.3^{^8}-2^{^{10}}.3^{^9}}{2^{^{10}}.3^{^8}+2^{^{10}}.3^{^8}.5}\)=\(\dfrac{2^{^{10}}.3^{^8}\left(1-3\right)}{2^{^{10}}.3^{^8}\left(1+5\right)}\)=\(\dfrac{1-3}{1+5}\)=\(\dfrac{1}{3}\)
45.94−2.69210.38+68.2045.94−2.69210.38+68.20=210.38−2.29.39210.38+28.38.22.5210.38−2.29.39210.38+28.38.22.5=210.38−210.39210.38+210.38.5210.38−210.39210.38+210.38.5=210.38(1−3)210.38(1+5)210.38(1−3)210.38(1+5)=1−31+51−31+5=13