[2.(70 - x) + 72] : 2 = 46
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2 bọn ngu dễ thế này ko cx ko xong
[2.(70-x)+72]:2=46
<=>2.(70-x)+72=92
<=>2(70-x)=20
<=>70-x=10
<=>x=60
[ 2. ( 70 - x ) + 72 ]: 2 =46
2. ( 70 - x ) + 72 = 46.2
2. ( 70 - x ) + 72 = 92
2. ( 70 - x ) =92-72
2. ( 70 - x ) =20
70-x=20:2
70-x=10
x=70-10
x=60
[ ( 2.x + 54 ) - 32 ] . 2 = 244
( 2.x + 54 ) - 32 = 244:2
( 2.x + 54 ) - 32 = 122
2.x + 54 = 122+32
2.x + 54 = 154
2.x =154-54
2x=100
x=100:2
x=50
a, ((2.x+54)-32).2=244
((2.x+54)-32)=244:2
((2.x+54)-32)=122
(2.x+54)=122+32
(2.x+54)=154
x+54=154:2
x+54=77
x=77-54
x=23
\(\left[3.\left(70-x\right)+5\right]:2=46\)
=> \(3.\left(70-x\right)+5=92\)
=> \(3.\left(70-x\right)=87\)
=> \(70-x=29\)
=> \(x=41\)
[ 3 . ( 70 - x )+ 5 ]: 2 = 46
[ 3 . ( 70 - x )+ 5 ] = 46 . 2
[ 3 . ( 70 - x )+ 5 ] = 92
3 . ( 70 - x ) = 92 - 5
3 . ( 70 - x ) = 87 : 3
70 - x = 29
x = 70 - 29
x = 41
# CHUC BAN HOK TOT
1) \(78+22+18=100+18=118.\)
2) \(94+563+\left(106-563\right)-\left(-70\right)=94+563+106-563+70\)
\(=\left(94+106\right)+\left(563-563\right)+70=270.\)
3) \(25.154-25+47.25=25.\left(154-1+47\right)=25.200=5000.\)
1: Ta có: \(\left|x^2-72\right|-2=70\)
\(\Leftrightarrow\left|x^2-72\right|=72\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-72=72\\x^2-72=-72\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x^2=144\\x^2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-12\\x=0\end{matrix}\right.\)
Vậy: S={0;-12;12}
2: Ta có: \(x^2-5\left|x\right|=14\)
\(\Leftrightarrow5\left|x\right|=x^2-14\)(*)
Trường hợp 1: x≥0
(*)\(\Leftrightarrow5x=x^2-14\)
\(\Leftrightarrow x^2-14=5x\)
\(\Leftrightarrow x^2-5x-14=0\)
\(\Leftrightarrow x^2-7x+2x-14=0\)
\(\Leftrightarrow x\left(x-7\right)+2\left(x-7\right)=0\)
\(\Leftrightarrow\left(x-7\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-7=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7\left(nhận\right)\\x=-2\left(loại\right)\end{matrix}\right.\)
Trường hợp 2: x<0
(*)\(\Leftrightarrow-5x=x^2-14\)
\(\Leftrightarrow x^2+5x-14=0\)
\(\Leftrightarrow x^2+7x-2x-14=0\)
\(\Leftrightarrow x\left(x+7\right)-2\left(x+7\right)=0\)
\(\Leftrightarrow\left(x+7\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+7=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-7\left(nhận\right)\\x=2\left(loại\right)\end{matrix}\right.\)
Vậy: S={-7;7}
\(a,96-3\left(x+8\right)=42\\ \Rightarrow3\left(x+8\right)=54\\ \Rightarrow x+8=18\\ \Rightarrow x=10.\\ b,15.5\left(x-25\right)-225=0\\ \Rightarrow75\left(x-25\right)-225=0\\ \Rightarrow75\left(x-25\right)=225\\ \Rightarrow x-25=3\\ \Rightarrow x=28.\\ c,250:x+15=25\\ \Rightarrow250:x=10\\ \Rightarrow x=25\\ d,36:\left(x-5\right)=2^2\\ \Rightarrow36:\left(x-5\right)=4\\ \Rightarrow x-5=9\\ \Rightarrow x=14.\\ e,\left[3.\left(70-x\right)+5\right]:2=46\\ \Rightarrow3.\left(70-x\right)+5=92\\ \Rightarrow3\left(70-x\right)=87\\ \Rightarrow70-x=29\\ \Rightarrow x=41.\)
2.
a, x-13=-46
=>x=(-46)+13
=>x=33
b, 4x-6=22
=>4x=22+6
=>4x=28
=>x=28:4
=>x=7
3.
a, 32=25
48=24.3
=>ƯCLN(32,48)=24=16
16=24
72=23.32
=>ƯCLN(16,72)=23=8
b,
24=23.3
60=22.3.5
=>BCNN(24,60)=23.3.5=120
72=23.32
180=22.32.5
=>BCNN(72,180)=23.32.5=360
Lời giải:
$[2(70-x)+72]:2=46$
$(140-2x+72):2=46$
$212-2x=46.2=92$
$2x=212-92=120$
$x=120:2=60$