Rút gọn hai biểu thức sau:
a) 5.7^12
7^10.5^10
b) 5^8.7^12-5^9.7^11
7^11.5^10+7^12.5^11
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Câu 1 xem kỉ đề
\(B,\frac{49^6.5-7^{11}}{\left(-7\right)^{10}.5-2.49^5}=\frac{7^{12}.5-7^{11}}{7^{10}.5-2.7^{10}}=\frac{7^{11}.\left(7.5-1\right)}{7^{10}.\left(5-2\right)}=\frac{7.34}{3}=\frac{238}{3}\)
a) A=212.35-\(\frac{2^{12}.3^6}{2^{12}}\)+93+84.35
=212.35-36+36+212.35
=213.35
b)B=496.5-5.\(\frac{7^{11}}{\left(-7\right)^{10}}-2.49^5\)
=496.5-7.5-2.495
=712.5-7.5-2.710
`a) ((-14).15)/(21.(-10))`
`=(-7.3.5.3)/(7.3.(-2).5)`
`=3/2`
`b) ((-7).12)/((-16).(-14))`
`=(-7.3.2.2)/(-2.2.2.(-7).2)`
`=(-3)/4`
`c) ((-11).(-5))/(15.22) `
`=(-11.(-5))/(3.5.11.2)`
`=1/6`
`d) ((-10).(-18))/((-6).25.7)`
`=(-5.2.-2.3.3)/(-2.3.5.5.7)`
`=6/35`
`e) (5.7-7.9)/(7.2+6.7)`
`=(7.(5-9))/(7.(2+6))`
`=-4/8`
`=-1/2`
`f) (11.9-22.3)/(33.2)`
`=(33.(3-2))/(33.2)`
`=1/2`
\(a,=-2\sqrt{5}+9\sqrt{5}-24\sqrt{5}-\sqrt{5}=-18\sqrt{5}\)
\(b,=2\sqrt{3}-5\sqrt{3}+4\sqrt{3}-7\sqrt{3}=-6\sqrt{3}\)
\(c,=3\sqrt{3}+7\sqrt{3}-9\sqrt{3}+11\sqrt{3}=12\sqrt{3}\)
a) Ta có: \(-\sqrt{20}+3\sqrt{45}-6\sqrt{80}-\dfrac{1}{5}\sqrt{125}\)
\(=-2\sqrt{5}+9\sqrt{5}-24\sqrt{5}-\dfrac{1}{5}\cdot5\sqrt{5}\)
\(=-17\sqrt{5}-\sqrt{5}=-18\sqrt{5}\)
b) Ta có: \(2\sqrt{3}-\sqrt{75}+2\sqrt{12}-\sqrt{147}\)
\(=2\sqrt{3}-5\sqrt{3}+4\sqrt{3}-7\sqrt{3}\)
\(=-6\sqrt{3}\)
\(\frac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}+9.5^{11}.7^{11}}\)
=\(\frac{5^{11}.7^{11}\left(7+1\right)}{5^{11}.7^{11}\left(5.7+9\right)}\)
= \(\frac{8}{35+9}\)
= \(\frac{8}{44}\)
= \(\frac{2}{11}\)
a)\(\frac{3^{10}.\left(-5\right)^{21}}{\left(-5\right)^{20}.3^{12}}=\frac{-5}{9}\)
b)\(\frac{\left(-11\right)^5.13^7}{11^5.13^8}=-\frac{1}{13}\)
c)\(\frac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\frac{2^{10}.3^9\left(3-1\right)}{2^9.3^{10}}=2\)
d(\(\frac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}+9.5^{11}.7^{11}}=\frac{5^{11}.7^{11}\left(7+1\right)}{5^{11}.7^{11}\left(35+9\right)}=\frac{1}{6}\)
\(\frac{5^{10}.7^{12}+5^{10}.7^{11}}{5^{12}.7^{11}+9.5^4.7^{11}}=\frac{5^{10}.7^{11}.\left(7+1\right)}{7^{11}.5^4\left(5^8+9\right)}=\frac{8.5^6}{\left(9+5^8\right)}=\frac{125000}{390634}=\frac{62500}{195317}\)
a) Đặt: A = \(\frac{5.7^{12}}{7^{10}.5^{10}}=\frac{5.7^2.7^{10}}{7^{10}.5^{10}}=\frac{7^2}{5^9}\)
b) Đặt: B = \(\frac{5^8.7^{12}-5^9.7^{11}}{7^{11}.5^{10}+7^{12}.5^{11}}=\frac{5^8.7.7^{11}-5.5^8.7^{11}}{7^{11}.5^{10}+7.7^{11}.5.5^{10}}\\ =\frac{5^8.7^{11}.\left(7-5\right)}{7^{11}.5^{10}.\left(1+7.5\right)}=\frac{2}{5^2.36}=\frac{2}{25.36}=\frac{1}{450}\)
a)\(\frac{5.7^{12}}{7^{10}.5^{10}}=\frac{5.7^{10}.7^2}{7^{10}.5.5^9}=\frac{7^2}{5^9}\)