720 : (x - 17 ) = 12
5x . 25 3 = 125 4
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`@` `\text {Ans}`
`\downarrow`
`x^3 = 125`
`=> x^3 = 5^3`
`=> x = 5`
Vậy, `x = 5`
_____
`4^5 \div 4^3`
`=`\(4^{5-3}\)
`= 4^2`
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\(8^{12}\cdot8^3\div8^{15}\)
`=`\(8^{12+3-15}\)
`=`\(8^0=1\)
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\(7^{15}\div7^{13}\)
`=`\(7^{15-13}\)
`=`\(7^2\)
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\(17^{15}\cdot17^{10}\div17^{22}\)
`=`\(17^{15+10-22}\)
`= 17^3`
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\(5^{10}\cdot25\div5^{11}\)
`=`\(5^{10}\cdot5^2\div5^{11}\)
`=`\(5^{10+2-11}\)
`= 5`
_______
\(15^{10}\cdot225\div15^{11}\)
`=`\(15^{10}\cdot15^2\div15^{11}\)
`=`\(15^{12}\div15^{11}\)
`= 15`
`@` `\text {Kaizuu lv uuu}`
\(x^3=125\)
\(\Rightarrow x^3=5^3\)
\(\Rightarrow x=3\)
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\(4^5:4^3\)
\(=4^{5-3}\)
\(=4^2=16\)
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\(8^{12}.8^3:8^{15}\)
\(=8^{15}:8^{15}\)
\(=1\)
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\(7^{15}:7^{13}\)
\(=7^{15-13}\)
\(=7^2=49\)
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\(17^{15}.17^{10}:17^{22}\)
\(=17^{25}:17^{22}\)
\(=17^3=4913\)
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\(5^{10}.25:5^{11}\)
\(=5^{10}.5^2:5^{11}\)
\(=5^{12}:5^{11}\)
\(=5^1=5\)
___________________
\(15^{10}.225:15^{11}\)
\(=15^{10}.15^2:15^{11}\)
\(=15^{12}:15^{11}\)
\(=15^1=15\)
__________________
* an . am = an+m
an : am = an-m
Chúc bạn học tốt
1) Ta có: \(\left(-\dfrac{2}{3}\right)^2\cdot\dfrac{-9}{8}-25\%\cdot\dfrac{-16}{5}\)
\(=\dfrac{4}{9}\cdot\dfrac{-9}{8}-\dfrac{1}{4}\cdot\dfrac{-16}{5}\)
\(=\dfrac{-1}{2}+\dfrac{4}{5}\)
\(=\dfrac{-5}{10}+\dfrac{8}{10}=\dfrac{3}{10}\)
2) Ta có: \(-1\dfrac{2}{5}\cdot75\%+\dfrac{-7}{5}\cdot25\%\)
\(=\dfrac{-7}{5}\cdot\dfrac{3}{4}+\dfrac{-7}{5}\cdot\dfrac{1}{4}\)
\(=\dfrac{-7}{5}\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=-\dfrac{7}{5}\)
3) Ta có: \(-2\dfrac{3}{7}\cdot\left(-125\%\right)+\dfrac{-17}{7}\cdot25\%\)
\(=\dfrac{-17}{7}\cdot\dfrac{-5}{4}+\dfrac{-17}{7}\cdot\dfrac{1}{4}\)
\(=\dfrac{-17}{7}\cdot\left(\dfrac{-5}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{17}{7}\)
4) Ta có: \(\left(-2\right)^3\cdot\left(\dfrac{3}{4}\cdot0.25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
\(=\left(-8\right)\cdot\left(\dfrac{3}{4}\cdot\dfrac{1}{4}\right):\left(\dfrac{9}{4}-\dfrac{7}{6}\right)\)
\(=\left(-8\right)\cdot\dfrac{3}{16}:\dfrac{54-28}{24}\)
\(=\dfrac{-3}{2}\cdot\dfrac{24}{26}\)
\(=\dfrac{-72}{52}=\dfrac{-18}{13}\)
x^3-1=(x-1)(x^2+x+1)
8x^3+1=(2x+1)(4x^2-2x+1)
x^3+1=(x+1)(x^2-x+1)
125-x^3=(5-x)(25+5x+x^2)
x^3+8y^3=x^3+(2y)^3
=(x+2y)(x^2-2xy+4y^2)
64y^3-125x^3
=(4y)^3-(5x)^3
=(4y-5x)(16y^2+20xy+25x^2)
\(27x^3-\dfrac{1}{8}=\left(3x\right)^3-\left(\dfrac{1}{2}\right)^3=\left(3x-\dfrac{1}{2}\right)\left(9x^2+\dfrac{3}{2}x+\dfrac{1}{4}\right)\)
\(a^6-b^3=\left(a^2\right)^3-b^3\)
\(=\left(a^2-b\right)\cdot\left(a^4+a^2b+b^2\right)\)
\(25.5.4.125.20.8\)
\(=\left(25.4\right).\left(5.20\right).\left(125.8\right)\)
\(=100.100.1000\)
\(=10000000\)
x-17=60
x=77
\(720:\left(x-17\right)=12\)
\(x-17=720:12\)
\(x-17=60\)
\(x=77\)
\(5^x.25^3=125^4\)
\(5^x.5^{2.3}=5^{3.4}\)
\(x+6=12\)
\(x=6\)