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a, \(2,5:4x=0,5:0,2\)
\(\Rightarrow4x=\dfrac{2,5.0,2}{0,5}\)
\(\Rightarrow4x=1\Rightarrow x=\dfrac{1}{4}\)
b, \(\dfrac{1}{5}x:3=\dfrac{2}{3}:0,5\)
\(\Rightarrow\dfrac{1}{5}x=\dfrac{3.\dfrac{2}{3}}{0,5}\)
\(\Rightarrow\dfrac{1}{5}x=4\Rightarrow x=20\)
c, \(1,25:0,8=\dfrac{3}{8}:0,2x\)
\(\Rightarrow0,2x=\dfrac{0,8.\dfrac{3}{8}}{1,25}\)
\(\Rightarrow0,2x=0,24\Rightarrow x=1,2\)
Chúc bạn học tốt!!
a, \(2,5:4x=0,5:0,2\)
\(2,5:4x=2,5\)
\(4x=2,5:2,5\)
\(4x=1\)
\(x=1:4\)
\(x=\dfrac{1}{4}\)
Vậy .............
b, \(\dfrac{1}{5}x:3=\dfrac{2}{3}\)
\(\dfrac{1}{5}x=\dfrac{2}{3}.3\)
\(\dfrac{1}{5}x=2\)
\(x=2:\dfrac{1}{5}\)
\(x=10\)
Vậy .....
c, \(1,25:0,8=\dfrac{3}{8}:0,2x\)
\(1,5625=\dfrac{3}{8}:0,2x\)
\(0,2x=\dfrac{3}{8}:1,5625\)
\(0,2x=0,24\)
\(x=0,24:0,2\)
\(x=1,2\)
Vậy ...
Các câu đúng: b,e
Các câu sai: a, c, d; f.
a) \(\left(-5\right)^2.\left(-5\right)^3=\left(-5\right)^5\);
c) \(\left(0,2\right)^{10}:\left(0,2\right)^5=\left(0,2\right)^{10-5}=0,2^5\);
d) \(\left[\left(-\dfrac{1}{7}\right)^2\right]^4=\left(-\dfrac{1}{7}\right)^{2.4}=\left(-\dfrac{1}{7}\right)^8\)
f \(\dfrac{8^{10}}{4^8}=\dfrac{\left(2^3\right)^5}{\left(2^2\right)^8}=\dfrac{2^{15}}{2^{16}}=\dfrac{1}{2}\)
1: \(=4^4\cdot\left(0.25\right)^4\cdot\left(\dfrac{1}{4}\right)^2=\dfrac{1}{16}\)
2: \(=\left(0.5\right)^4\cdot2^4\cdot2^4=16\)
3: \(=\left(-0.125\right)^7\cdot8^7\cdot8^3=-512\)
4: \(=0.1^7\cdot10^7\cdot10^6=1000000\)
5: \(=\left(-2\right)^{13}\cdot2^8=-2^{21}\)
6: \(=\left(-3\right)^7\cdot\left(-3\right)^4=\left(-3\right)^{11}\)
\(a,\) \(\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}\)
\(=\frac{2^{12}.3^{10}+\left(2.3\right)^9.2^3.3.5}{2^{12}.3^{12}-\left(2.3\right)^{11}}\)
\(=\frac{2^{12}.3^{10}+2^9.3^9.2^3.3.5}{2^{12}.3^{12}-2^{11}.3^{11}}\)
\(=\frac{2^{12}.3^{10}+2^{12}.3^{10}.5}{2^{12}.3^{12}-2^{11}.3^{11}}\)
\(=\frac{\left(2^{12}.3^{10}\right)\left(1+5\right)}{\left(2^{11}.3^{11}\right)\left(2.3-1\right)}\)
\(=\frac{\left(2^{12}.3^{10}\right).6}{\left(2^{11}.3^{11}\right).5}\)
\(=\frac{2.6}{3.5}\)
\(=\frac{2.2}{5}\)
\(=\frac{4}{5}\)
\(b,\) \(\frac{2^{15}.9^4}{6^3.8^3}\)
\(=\frac{2^{15}.3^8}{2^3.3^3.2^9}\)
\(=\frac{2^{15}.3^8}{2^{12}.3^3}\)
\(=2^3.3^5\)
\(=8.243\)
\(=1944\)
Chúc bạn học tốt ^^
a) \(\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}=\frac{\left(2^2\right)^6.\left(3^2\right)^5+6^9.120}{\left(2^3\right)^4.3^{12}-6^{11}}=\frac{2^{12}.3^{10}+6^9.120}{2^{12}.3^{12}-6^{11}}=\frac{6^{10}.4+6^{10}.20}{6^{12}-6^{11}}=\frac{6^{10}.\left(4+20\right)}{6^{11}.\left(6-1\right)}=\frac{6^{11}.4}{6^{11}.5}=\frac{4}{5}\)
b) \(\frac{2^{15}.9^4}{6^3.8^3}=\frac{2^{15}.\left(3^2\right)^4}{\left(2.3\right)^3.\left(2^3\right)^3}=\frac{2^{15}.3^8}{2^3.3^3.2^9}=\frac{2^{15}.3^8}{2^{12}.3^3}=2^3.3^5=1944\)
c) \(\frac{8^{10}+4^{10}}{8^4+4^{11}}=\frac{\left(4.2\right)^{10}+4^{10}}{\left(2^3\right)^4+4^6.4^5}=\frac{4^{10}.2^{10}+4^{10}}{2^{12}+4^6.4^5}=\frac{4^{10}.\left(2^{10}+1\right)}{4^6+4^6.2^{10}}=\frac{4^{10}.\left(2^{10}+1\right)}{4^6.\left(1+2^{10}\right)}=\frac{4^{10}}{4^6}=4^4=256\)
\(a,8\cdot\frac23:4\cdot\frac13-10=\frac{16}{3}:\frac43-10\)
\(=\frac{16}{3}\cdot\frac34-10=4-10=-6\)
\(b,\frac25+\frac35:\left(-\frac{9}{10}\right)-\frac13\)
\(=\frac25+\frac35\cdot\left(-\frac{10}{9}\right)-\frac13\)
\(=\frac25+\left(-\frac23\right)-\frac13=\frac25-\left(\frac23+\frac13\right)\)
\(=\frac25-1=\frac25-\frac55=-\frac35\)
\(c,-1,25\cdot\left(-4,1\right)\cdot8+0,2\)
\(=\left(-1,25\cdot8\right)\cdot\left(-4,1\right)+0,2\)
\(=\left(-10\right)\cdot\left(-4,1\right)+0,2\)
\(=41+0,2=41,2\)
a; 8\(\frac23\) : 4\(\frac13\) - 10
= \(\frac{26}{3}\) : \(\frac{13}{3}\) - 10
= \(\frac{26}{3}\times\frac{3}{13}\) - 10
= 2 - 10
= - 8
b; \(\frac25+\frac35\) : (- \(\frac{9}{10}\)) - \(\frac13\)
= \(\frac25\) + \(\frac35\) x (- \(\frac{10}{9}\)) - \(\frac13\)
= \(\frac25\) - \(\frac23\) - \(\frac13\)
= \(\frac25\) - (\(\frac23+\frac13\))
= \(\frac25\) - 1
= \(\frac25\) - \(\frac55\)
= - \(\frac35\)
c; -1,25 x (-4,1) x 8 + 0,2
= (1,25 x 8) x 4,1 + 0,2
= 10 x 4,1 + 0,2
= 41 + 0,2
= 41,2