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a) \(2\left(2x-7\right)^2=18\)
\(\Leftrightarrow\left(2x-7\right)^2=9\)
\(\Leftrightarrow\left(2x-7\right)^2=3^2\)
\(\Leftrightarrow2x-7=3\)
\(\Leftrightarrow2x=10\)
\(\Leftrightarrow x=5\)
2.(2X-7)^2= 18
(2X-7)^2=18:2
(2x-7)^2= 9
(2x-7)^2 = 3^2 = (-3)^2
=> (2x-7)^2 = 3^2 và (2x-7)^2 = (-3)^2
a) \(2\left(x-5\right)-3\left(x+7\right)=14\)
\(\Leftrightarrow2x-10-3x-21=14\)
\(\Leftrightarrow-x-31=14\)
\(\Leftrightarrow-x=45\Leftrightarrow x=-45\)
b) \(5\left(x-6\right)-2\left(x+3\right)=12\)
\(\Leftrightarrow5x-30-2x-6=12\)
\(\Leftrightarrow3x-36=12\)
\(\Leftrightarrow3x=48\Leftrightarrow x=16\)
c) \(3\left(x-4\right)-\left(8-x\right)=12\)
\(\Leftrightarrow3x-12-8+x=12\)
\(\Leftrightarrow4x-20=12\)
\(\Leftrightarrow4x=32\Leftrightarrow x=8\)
d) \(-7\left(3x-5\right)+2\left(7x-14\right)=28\)
\(\Leftrightarrow-21x+35+14x-28=28\)
\(\Leftrightarrow-7x+35=0\Leftrightarrow x=5\)
\(\frac{12}{x}\)+ 9 = 45
\(\frac{12}{x}\) = 36
x = \(\frac{12}{36}\)= 1/3
b) 5x + 8- 4x = 72
(5x-4x) +8 = 72
x + 8 = 72
x = 72-8
x= 64
\(a,\frac{12}{x}+9=45\)
\(\Rightarrow\frac{12}{x}=45-9=36\)
\(\Rightarrow x=12:36=\frac{1}{3}\)
\(b,5x+8-4x=72\)
\(\Rightarrow5x-4x=72-8\)
\(\Rightarrow x=64\)
a)\(5\le2.x< 13\)''
\(\frac{5}{2}\le x< \frac{13}{2}\)( chia cho 2)
b)\(5< 4.x+1\le17\)
\(5-1< 4x\le17-1\)( trừ cho 1 )
\(4< 4x\le16\)
\(\frac{4}{4}< x\le\frac{16}{4}\)
\(1< x\le4\)
c) \(x+\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}=\frac{1}{8}\)
\(x+\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}=8\)
\(x+1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}=8\)( Áp dụng \(\frac{1}{a.\left(a+1\right)}=\frac{1}{a}-\frac{1}{a+1}\))
\(x+1-\frac{1}{6}=8\)
\(x=8-1+\frac{1}{6}\)
\(x=\frac{43}{6}\)
12-4x+(x-8)=14
4x+(x-8)=12-14
4x+(x-8)=-2
x+(x-8)=-2:4
x+(x-8)=-1/2
x-8=-1/2-x
x-x=-1/2+8
0x=15/2
X=0
Đúng thì cho xin yk
12-4x+(x-8)=14
12-4x+x-8=14
(-4x+x)+(12-8)=14
-3x+4=14
-3x=14-4
-3x=10
x=10 phần -3
x=âm 10 phần 3
\(x=\frac{-10}{3}\)
\(x=-\frac{10}{3}\)