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a) \(326-2x=78\Rightarrow2x=326-78=248\)
\(\Rightarrow x=248:2=124\)
b) \(42.5-\left(3x+6\right)=3^4\Rightarrow210-\left(3x+6\right)=81\)
\(\Rightarrow3x+6=210-81=129\Rightarrow3x=129-6=123\)
\(\Rightarrow x=123:3=41\)
a, 326 -2x =78
\(\Rightarrow\)2x=326-78=248
\(\Rightarrow\)x=248/2=124
b,\(42.5-\left(3x+6\right)=3^4\)
\(\Rightarrow\)\(210-3x-6=81\)
\(\Rightarrow\)3x=123
\(\Rightarrow\)x=123/3=41
c, \(4^x:64=4^{250}\)
\(\Rightarrow\)\(4^x:4^3=4^{250}\)
\(\Rightarrow\)x=253
d, \(30x+1+2+3+...+30=495\)
\(\Rightarrow\)\(30x+465=495\)
\(\Rightarrow\)\(x=1\)
Bài 1:
Ta có: \(4-2\left(x+1\right)=2\)
\(\Leftrightarrow2\left(x+1\right)=2\)
\(\Leftrightarrow x+1=1\)
hay x=0
Bài 2:
Ta có: \(\left|2x-3\right|-1=2\)
\(\Leftrightarrow\left|2x-3\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)
B1 a A = 2/3+1/6-1/2=5/6-1/2=2/6=1/3
b B=3.{5.[(25+8):11]-16}+2015=3.{5.[33:11]-16}=3.{5.3-16}+2015
=3.{15-16}+2015=3.(-1)+2015=-3+2015=2012
B2 8.6+288 :(x-3)2=50
8.6+288:(x-3)=50:2
8.6+288:(x-3)=25
288:(x-3)=25-8.6
288:(x-3)=-23
x-3=-23.288
X-3=-6624
x=-6624+3
X=-6627
bai 1: a) \(A=\frac{2}{3}+\frac{5}{6}:5-\frac{1}{18}.\left(-3\right)^2\)
\(A=\frac{2}{3}+\frac{1}{6}-\frac{1}{18}.9\)
\(A=\frac{4}{6}+\frac{1}{6}-\frac{1}{2}\)
\(A=\frac{5}{6}-\frac{3}{6}\)
\(A=\frac{2}{6}=\frac{1}{3}\)
b) \(B=3\left\{5.\left[\left(5^2+2^3\right):11\right]-16\right\}+2015\)
\(B=3\left\{5.\left[\left(25+8\right):11\right]-16\right\}+2015\)
\(B=3\left\{5.\left[33:11\right]-16\right\}+2015\)
\(B=3\left\{5.3-16\right\}+2015\)
\(B=3\left\{15-16\right\}+2015\)
\(B=3.\left(-1\right)+2015\)
\(B=-3+2015\)
\(B=2012\)
bai 2: \(6.8+288:\left(x-3\right).2=50\)
\(48+288:\left(x-3\right).2=50\)
\(288:\left(x-3\right).2=50-48\)
\(288:\left(x-3\right).2=2\)
\(\left(x-3\right).2=288:2\)
\(\left(x-3\right).2=144\)
\(x-3=144:2\)
\(x-3=72\)
\(x=75\)
vay \(x=75\)
a, 3.(2\(x\) + 4) + 198 = (-3)2.10
3.(2\(x\) + 4) + 198 = 90
3.(2\(x\) + 4) = 90 - 198
3.(2\(x\) + 4) = - 108
2\(x\) + 4 = -108 : 3
2\(x\) + 4 = -36
2\(x\) = - 36 - 4
2\(x\) = - 40
\(x\) = -40 : 2
\(x\) = - 20
b, 2.(\(x\) + 7) - 6 = 18
2.(\(x\) + 7) = 18 + 6
2.(\(x\) + 7) =24
\(x\) + 7 = 24 : 2
\(x\) + 7 = 12
\(x\) = 12 - 7
\(x\) = 5
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