-3×7 mũ4+7 mũ3 / 7 mũ5×6-7 mũ3×2
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(5x-24).73=2.74
5x-16=2.(74:73)
5x-16=2.7
5x-16=14
5x=14+16
5x=30
x=30:5=6
S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27
= (1 + 2) + (22 + 23) + (24 + 25) + (26 + 27)
= (1 + 2) + 22(1 + 2) + 24(1 + 2) + 26(1 + 2)
= (1 + 2)(1 + 22 + 24 + 26)
= 3(1 + 22 + 24 + 26) \(⋮3\)(ĐPCM)
2S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27
S = (1+2 ) + (22 + 23 ) + (24 + 25 ) + (26 +27)
S = 3 + 22(1+2) + 24(1+2) + 26(1+2)
S = 3+22.3 + 24.3 + 26 .3
S = 3(1+22 + 24 + 26 ) \(⋮\) 3
=> đpcm
\(\left(6x-3^3\right).5^3=3.5^4\)
\(\Rightarrow\left(6x-27\right)=3\left(5^4\div5^3\right)\)
\(\Rightarrow\left(6x-27\right)=3.5\)
\(\Rightarrow6x-27=15\)
\(\Rightarrow6x=42\)
\(\Rightarrow x=7\)
1)Tính:
a)\(4^2\cdot2=\left(2^2\right)^2\cdot2=2^4\cdot2=2^5=32\)
b)\(36^2:6^2=\left(36:6\right)^2=6^2=48\)
c)\(\left(\frac{2}{5}\right)^{10}:\left(\frac{4}{25}\right)^2=\left(\frac{2}{5}\right)^{10}\cdot\left(\frac{25}{4}\right)^2=\)\(\left(1\right)^{10}\cdot\left(\frac{5}{2}\right)^2=1\cdot\frac{5^2}{2^2}=1\cdot\frac{25}{4}=\frac{25}{4}\)
a
\(4^2.2=16.2=32\)
b\(36^2:6^2=36.36:6.6=36.36:36=36\)
c
\(324-\left\{38+\left[7\cdot3-24:6+\left(9-7\right)^3\right]\right\}:15\)
\(=324-\left\{38+21-4+2^3\right\}:15\)
\(=324-\left\{38+17+8\right\}:15\)
\(=324-\dfrac{63}{15}=324-4,2=319,8\)
\(\frac{-3.7^4+7^3}{7^5.6-7^3.2}=\frac{7^3\left(-3.7+1\right)}{7^3\left(7^2.6-2\right)}=\frac{-21+1}{49.6-2=4}=\frac{-20}{290}\)