tìm x biết :
315+[125-x]=435
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a) ( x - 15 ) - 75 = 0
<=> x - 15 = 75
<=> x = 90
b) 575 - ( 6x + 70 ) = 445
<=> 6x + 70 = 130
<=> 6x = 60
<=> x = 10
c) 315 + ( 125 - x ) = 435
<=> 125 - x = 120
<=> x = 5
a) x - 105 : 21 = 15
x - 5 = 15
=> x = 20
b) ( x - 105 ) : 21 = 15
x - 105 = 315
=> x = 420
c) 315 + ( 125 - x ) = 435
125 - x = 120
=> x = 5
a) \(315+\left(125-x\right)=435\)
\(\Leftrightarrow125-x=435-315\)
\(\Leftrightarrow125-x=120\)
\(\Leftrightarrow x=125-120\)
\(\Leftrightarrow x=5\)
b) \(x:41=32\)
\(\Leftrightarrow x=32\cdot41\)
\(\Leftrightarrow x=1312\)
c) \(\left(x-105\right):21=15\)
\(\Leftrightarrow x-105=15\cdot21\)
\(\Leftrightarrow x-105=315\)
\(\Leftrightarrow x=315+105\)
\(\Leftrightarrow x=420\)
d) \(x-105:21=15\)
\(\Leftrightarrow x-5=15\)
\(\Leftrightarrow x=15+5\)
\(\Leftrightarrow x=20\)
a, 315 + ( 125 - x ) = 435
( 125 - x) = 435 - 315
( 125 - x ) = 320
x = 320 - 125
x = 195
a) 575 - ( 6x + 70 ) = 447
( 6x + 70 ) = 575 - 447
( 6x - 70 ) = 128
6x = 128 + 70
6x = 198
x = 198 : 6
x = 33
Tìm x, biết
a/ ( x - 15 ) - 75 = 0
( x - 15 ) = 0 + 75
( x - 15 ) = 75
x = 75 + 15
x = 100
b/ 315 + ( 125 - x ) = 435
( 125 - x ) = 435 - 315
( 125 - x ) = 120
x = 125 - 120
x = 5
c/ 2031 - x + 102 = 1003
2031 - x = 1003 -102
2031 - x = 901
x = 2031 - 901
x = 1130
d/ x + 1002 = 1003 + 4327
x + 1002 = 5330
x = 5330 - 1002
x = 4328
Hok tốt
Trả lời :
a) (x - 15) - 75 = 0
x - 15 = 0 + 75
x - 15 = 75
x = 75 + 15
x = 90
(các câu kia tương tự)
Bai 1 :
a/ \(x:1,4+2,8=8,4\)
\(x:1,4=8,4-2,8\)
\(x:1,4=5,6\)
\(x=5,6\times1,4\)
\(x=7,84\)
b/ \(2,8:x-1,5=2,3:5,75\)
\(2,8:x-1,5=\frac{2}{5}\)
\(2,8:x=\frac{2}{5}+1,5\)
\(2,8:x=\frac{19}{10}=1,9\)
\(\Rightarrow x=2,8:1,9=\frac{28}{19}\)
Bai 2 :
a/ \(575-\left(6\times x+70\right)=445\)
\(6\times x+70=575-445\)
\(6\times x+70=130\)
\(6\times x=130-70\)
\(\Rightarrow6\times x=60\Rightarrow x=10\)
b/ \(315+\left(125-x\right)=435\)
\(125-x=435-315\)
\(125-x=120\)
\(\Rightarrow x=5\)
c/ \(\left(x-105\right):21=15\)
\(x-105=15\times21\)
\(x-105=315\)
\(\Rightarrow x=420\)
d/ \(3636:\left(12\times x-91\right)=36\)
\(12\times x-91=3636:36\)
\(12\times x-91=101\)
\(12\times x=101+91\)
\(12\times x=192\)
\(\Rightarrow x=16\)
e/ \(12\times\left(x-5\right)+73=20\)
\(12\times\left(x-5\right)=20-73\)
\(12\times\left(x-5\right)=-53\)
\(x-5=-53:12\)
\(x-5=\frac{-53}{12}\)
\(\Rightarrow x=\frac{-53}{12}+5\)
\(\Rightarrow x=\frac{7}{12}\)
f/ \(\left[\left(10-x\right)\times2+5\right]:3-2=3\)
\(\left[\left(10-x\right)\times2+5\right]:3=3+2\)
\(\left[\left(10-x\right)\times2+5\right]:3=5\)
\(\left[\left(10-x\right)\times2+5\right]=5\times3\)
\(\left(10-x\right)\times2+5=15\)
\(\left(10-x\right)\times2=15-5\)
\(\left(10-x\right)\times2=10\)
\(10-x=10:2\)
\(10-x=5\)
\(\Rightarrow x=5\)
315+[125-x]=435
125-x=435-315
125-x=120
x=125-120
x=5
\(315+\left(125-x\right)=435\)
\(125-x=435-315\)
\(125-x=120\)
\(x=125-120\)
\(x=5\)