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Bài 1:
a: \(\Leftrightarrow3^x\cdot10=810\)
\(\Leftrightarrow3^x=81\)
hay x=4
c: \(\Leftrightarrow5^x\cdot5+5^x\cdot\dfrac{1}{25}=126\)
\(\Leftrightarrow5^x\cdot\dfrac{126}{25}=126\)
\(\Leftrightarrow5^x=25\)
hay x=2
Bài 2:
a: \(27^{11}=3^{33}\)
\(81^8=3^{32}\)
mà 33>32
nên \(27^{11}>81^8\)
c: \(625^5=\left(5^4\right)^5=5^{20}\)
\(125^7=\left(5^3\right)^7=5^{21}\)
mà 20<21
nên \(625^5< 125^7\)
ta có:\(x-\frac{1}{4}=\frac{5}{8}\cdot\frac{2}{3}\)
=>\(x-\frac{1}{4}=\frac{5}{12}\)
=>\(\frac{2}{3}\)
b)\(\frac{x}{126}=\frac{-20}{63}\)
=>\(\frac{x}{126}=\frac{-40}{126}\)
=>x=-40
a)\(X-\frac{1}{4}\)=\(\frac{-3}{8}\)x\(\frac{2}{5}\)
\(X-\frac{1}{4}=\frac{-6}{40}\)
\(X\)=\(\frac{-6}{40}\)+\(\frac{1}{4}\)
\(X\)=\(\frac{-6}{40}+\frac{10}{40}\)
\(X\)=\(\frac{4}{40}\)=\(\frac{1}{4}\)
\(4) 10-x:2=1 \)
\(=> x:2=10-1\)
\(=> x:2=9\)
\(=> x=9.2\)
\(=> x=18\). Vậy \(x=18\)
\(5) x:4+3.2=7\)
\(=> x:4+6=7\)
\(=> x:4=7-6\)
\(=> x:4=1\)
\(=> x=4\). Vậy \(x=4\)
\(6) 2:x+5=6\)
\(=> 2:x=6-5\)
\(=> 2:x=1\)
\(=> x=2\).Vậy \(x=2\)
\(7) 2.x.3.5=30\)
\(=> 2x.15=30\)
\(=>2x=30:15\)
\(=> 2x=2\)
\(=> x=1\).Vậy \(x=1\)
\(8)2.x:10.2=1\)
\(=> 2x=1:2.10\)
\(=> 2x=5\)
\(=>x=5:2\)
\(=> x=\frac{5}{2}\).Vậy \(x=\frac{5}{2}\)
\(9)18:x-5.2=8\)
\(=> 18:x-10=8\)
\(=>18:x=8+10\)
\(=>18:x=18\)
\(=> x=1\).Vậy \(x=1\)
\(10)5.5-2:x=24\)
\(=>25-2:x=24\)
\(=> 2:x=25-24\)
\(=>2:x=1\)
\(=>x=2\).Vậy \(x=2\)
a) x -1/4 = -3/8 . 2/5
x - 1/4 = -3/20
x = -3/20 + 1/4
x = 1/10
b) x/126 = -7/24 . -6/11
x/126 = 7/44
\(\Rightarrow\)x = rỗng
a, x- 1/4 = (-3/20)
x= 1/10
b, x/126 = (7/44)
x = 441/22