625^13 :125^15
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12517 \(=\left(5^3\right)^{17}=5^{51}\)
\(625^{13}=\left(5^4\right)^{13}=5^{52}\)
Ta có:
551 < 552
\(\Rightarrow\) 12517 < 62513
a, 68 + 42 x 5 - 625 : 25
= 68 + 210 - 25
= 278 - 25
= 253
b, 15 x { 37 + 8 + 20 } + 15 x { 13 + 22 }
= 15 x 65 + 15 x 35
= 15 x { 65 + 35 }
= 15 x 100
= 1500
c, 125 x 56 x 3
= 7000 x 3
= 21000
d, 249 - { 49 - 100 }
= 249 - 49 + 100
= 200 + 100
= 300
e, 1/2 + 1/4 + 1/ 8 + 1/32 + 1/64 + 1/128
= 1/1 - 1/2 + 1/2 - 1/4 + 1/4 - 1/8 + 1/8 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128
= 1/1 - 1/128
= 127/128
A, \(68+42\times5-625:25\)
= 68 +210 - 25
= 278 - 25
= 253
B,\(15\times\left(37+8+20\right)+15\times\left(13+22\right)\)
= \(15\times\left(37+8+20+13+22\right)\)
=\(15\times100\)
= 1500
C,\(125\times56\times3\)
= \(125\times8\times7\times3\)
= \(1000\times21\)
= 21000
D, 249 - { 49 - 100 }
= 249 - 49 -100
= 200 - 100
= 100
E, \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\)(mình sửa lại đề chút xíu nha, nó cứ bị sai sai sao ấy)
= \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+\frac{1}{16}-\frac{1}{32}+\frac{1}{32}-\frac{1}{64}+\frac{1}{64}-\frac{1}{128}\)
= \(1-\frac{1}{128}\)
=\(\frac{128}{128}-\frac{1}{128}\)
= \(\frac{127}{128}\)
\(\left(\frac{-1}{625}\right)^{13}=\left(\frac{-1}{5^4}\right)^{13}=\frac{\left(-1\right)^{13}}{\left(5^4\right)^{13}}=\frac{-1}{5^{52}}\)
\(\left(\frac{-1}{125}\right)^{17}=\left(\frac{-1}{5^3}\right)^{17}=\frac{\left(-1\right)^{17}}{\left(5^3\right)^{17}}=\frac{-1}{5^{51}}\)
Vì 552>551 nên \(\frac{-1}{5^{52}}>\frac{-1}{5^{51}}\) hay \(\left(\frac{-1}{625}\right)^{13}>\left(\frac{-1}{125}\right)^{17}\)
Chú ý nhé, so sánh 2 phân số có tử âm và mẫu dương ngược với so sánh 2 phân số có tử mẫu đều dương: Trong 2 phân số có cùng tử âm ( mẫu là dương), phân số nào có mẫu lớn hơn thì lớn hơn
Ta có:
\(125^{36}=\left(5^3\right)^{36}=5^{108}=5^{60}.5^{48}=5^{60}.\left(5^2\right)^{24}\)
\(=5^{60}.25^{24}\)
\(16^{24}.625^{15}=16^{24}.\left(5^4\right)^{15}=16^{24}.5^{60}\)
Vì \(25>16\) nên \(25^{24}>16^{24}\)=> \(5^{60}.25^{24}>5^{60}.16^{24}\)
Vậy \(125^{36}>16^{24}.625^{15}\)
T**k mik nhé!
\(\left(x-\dfrac{2}{15}\right)^3=\dfrac{8}{125}\\ \Rightarrow\left(x-\dfrac{2}{15}\right)^3=\left(\dfrac{2}{5}\right)^3\\ \Rightarrow x-\dfrac{2}{15}=\dfrac{2}{5}\\ \Rightarrow x=\dfrac{2}{5}+\dfrac{2}{15}\\ \Rightarrow x=\dfrac{6}{15}+\dfrac{2}{15}\\ \Rightarrow x=\dfrac{8}{15}\\ \left(\dfrac{4}{5}\right)^{2x+5}=\dfrac{256}{625}\\ \Rightarrow\left(\dfrac{4}{5}\right)^{2x+5}=\left(\dfrac{4}{5}\right)^4\\ \Rightarrow2x+5=4\\ \Rightarrow2x=4-5\\ \Rightarrow2x=-1\\ \Rightarrow x=-\dfrac{1}{2}\)
\(\left(x-\dfrac{2}{15}\right)^3=\dfrac{8}{125}\)
\(\left(x-\dfrac{2}{15}\right)^3=\left(\dfrac{2}{5}\right)^3\)
\(x-\dfrac{2}{15}=\dfrac{2}{5}\)
\(x=\dfrac{2}{5}+\dfrac{2}{15}\)
\(x=\dfrac{8}{15}\)
\(\left(\dfrac{4}{5}\right)^{2x+5}=\dfrac{256}{625}\)
\(\left(\dfrac{4}{5}\right)^{2x+5}=\left(\dfrac{4}{5}\right)^4\)
\(2x+5=4\)
\(2x=-1\)
\(x=-0,5\)
\(\frac{27^2.15^3.125^{17}.10^{10}.3^8.512+1024.25^{28}.12^6.15^7}{125.6^{17}+625^{12}.6^{13}.125^2.25^5.16}\)
=\(\frac{3^6.3^3.5^3.5^{34}.2^{10}.5^{10}.3^8.2^9+2^{10}.5^{56}.3^6.2^{12}.3^7.5^7}{5^{63}.6^{17}+5^{48}.6^{13}.5^6.2^4}\)=\(\frac{3^{17}.5^{47}.2^{19}+2^{22}.5^{63}.3^{13}}{5^{63}.6^{17}+5^{48}.6^{13}.5^6.2^4}=\frac{3^{13}.5^{47}.2^{19}.3^4+2^{19}.5^{47}.3^{13}.2^3.5^{16}}{5^{54}.6^{13}.5^9+5^{54}.6^{13}.2^4}\)
=\(\frac{3^{13}.5^{47}.2^{19}\left(3^4+2^3.5^{16}\right)}{5^{54}.6^{13}\left(5^9+2^4\right)}=\frac{6^{13}.2^6.5^{47}\left(3^4+2^3.5^{16}\right)}{5^7.5^{47}.6^{13}\left(5^9+2^4\right)}=\frac{2^6\left(3^4+2^3.5^{16}\right)}{5^7\left(5^9+2^4\right)}\)
Bạn hãy tự giải nốt
`@` `\text {Ans}`
`\downarrow`
\(625^{13}\div125^{15}\)
`=`\(\left(5^4\right)^{13}\div\left(5^3\right)^{15}\)
`=`\(5^{52}\div5^{45}\)
`=`\(5^7\)
\(625^{13}:125^{15}\\ =\left(5^4\right)^{13}:\left(5^3\right)^{15}\\ =5^{52}:5^{45}\\ =5^7\)