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575- [6x+70] = 445 315 +[125-x] = 435 f 541+[218-x]=435
6x+70 =575-445 125-x = 435- 315 218-x = 541-435
6x+70 = 130 125-x =120 218-x =106
6x = 130-70 x = 125 - 120 x = 218-106
6x = 60 x = 5 x = 112
x = 60:6
x = 10
bạn ơi khó hiểu quá,.,.,.
\(\orbr{\begin{cases}\\\end{cases}}\)
a)13-2(x+1)=7
2.(x+1)=13-7
2.(x+1)=6
x+1=6/2
x+1=3
x=3-1
x=2
a, 13 - 2 ( x + 1 ) = 7
2 .( x + 1 ) = 13 - 7
2 .( x + 1 ) = 6
x + 1 = 6 : 2
x + 1 = 3
x = 3 - 1
x = 4
\(a,\Rightarrow6x+70=130\Rightarrow6x=60\Rightarrow x=10\\ b,\Rightarrow240=\left(x+70\right):14-40\\ \Rightarrow\left(x+70\right):14=280\\ \Rightarrow x+70=3920\Rightarrow x=3850\\ c,\Rightarrow x-15=75\Rightarrow x=90\\ d,\Rightarrow\left(x+175\right):5=680-30=650\\ \Rightarrow x+175=3250\Rightarrow x=3075\\ e,\Rightarrow x-4867=1004523\Rightarrow x=1009390\\ f,\Rightarrow x+32-17=24\Rightarrow x=9\\ g,\Rightarrow3\left(x+1\right)=54\Rightarrow x+1=18\Rightarrow x=17\\ h,\Rightarrow19\left(35:x+3\right)=152\\ \Rightarrow35:x+3=8\Rightarrow35:x=11\Rightarrow x=\dfrac{35}{11}\)
câu d mk làm sai rồi
d) (x-15)-75=0
x-15=0+75=75
x=75+15=90
a) ( x - 15 ) - 75 = 0
x - 15 = 75
x = 75 + 15
x = 90
Vậy x = 90
b) 575 - ( 6x + 70 ) = 445
6x + 70 = 575 - 445
6x + 70 = 130
6x = 60
x = 10
Vậy x = 10
c) 315 + ( 125 - x ) = 435
125 - x = 120
x = 125 - 120
x = 5
Vậy x = 5
d) x - 105 : 21 = 15
x - 5 = 15
x = 20
Vậy x = 20
e) ( x - 105 ) : 21 = 1
x - 105 = 21
x = 21 + 105
x = 126
Vậy x = 126
thanks
1. Thực hiện phép tính bằng cách hợp lí :
a) (-46) + (-125) + 46 + 25 = [(-46)+46] + [(-125)+25]
= 0+(-100) = -100
b) 25.(-15) + 25.(-5) + (-20).75 = 25.[(-15)+(-5)] + (-20).75
= 25.(-20) + (-20).75 = (-20).(25+75) = (-20).100 = -2000
c) (-151)+(-37)+(-42)+(-63)+142 =(-151)+[(-37)+(-63)]+[(-42)+142]
= (-151) + [(-100) + 100] = -151
d)32+(-149)+(-311)+(-89)+(-51) = 32+[(-149)+(-51)] + [(-311)+(-89)]
= 32+[(-200)+(-400)] = 32+(-600) = -568
e)-65.(87-17)-87.(17-65) = (-65).87 - (-65).17 - 87.17 + 87.65
= (-65).87 + 65.17 - 87.17 + 87.65 = [(-65).87+87.65] + 65.(17-87)
= 65.(-70) = -4550
g) -43.(53-16) - 53.(16-43) = (-43).53 - (-43).16 - 53.16 + 53.43
= (-43).53 + 43.16 - 53.16 + 53.43 = [(-43).53+53.43] + 16.(43-53)
= 16.(-10) = -160
a: \(15\left(x-15\right)=0\)
mà 15>0
nên x-15=0
=>x=15
c: (x-15)-75=0
=>x-15=75
=>x=75+15=90
b: 32(x-10)=32
=>x-10=1
=>x=10+1=11
d: 575-(6x+70)=445
=>6x+70=575-445=130
=>6x=60
=>x=10
e: 315+(125-x)=435
=>440-x=435
=>x=440-435=5
g: x-105:21=15
=>x-5=15
=>x=15+5=20
h: \(231-\left(x-6\right)=1339:13\)
=>231-(x-6)=103
=>x-6=231-103=128
=>x=128+6=134
i: 70-5(x-3)=45
=>5(x-3)=70-45=25
=>x-3=5
=>x=5+3=8
k: 13-2(x+1)=7
=>2(x+1)=13-7=6
=>x+1=3
=>x=2
i: \(420+65\cdot4=\left(x+175\right):5+30\)
=>\(\dfrac{x+175}{5}=390+65\cdot4=390+260=650\)
=>x+175=3250
=>x=3250-175=3075
l: \(32\cdot15:2=\left(x+70\right):14-40\)
=>\(\left(x+70\right):14-40=16\cdot15=240\)
=>\(\left(x+70\right):14=240+40=280\)
=>\(x+70=14\cdot280=3920\)
=>x=3920-70=3850
m: \(165-\left(35:x+3\right)\cdot19=13\)
=>\(\left(35:x+3\right)\cdot19=165-13=152\)
=>35:x+3=152:19=8
=>35:x=8-3=5
=>x=35:5=7
n: \(1+2+3+4+...+x=528\)
=>\(\dfrac{x\left(x+1\right)}{2}=528\)
=>\(x\left(x+1\right)=528\cdot2=1056\)
=>\(x^2+x-1056=0\)
=>(x-32)(x+31)=0
=>\(\left[{}\begin{matrix}x=32\left(nhận\right)\\x=-31\left(loại\right)\end{matrix}\right.\)
p: \(\left(2x-1\right)+\left(4x-2\right)+...+\left(400x-200\right)=5+10+...+1000\)
=>\(\left(2x-1\right)\left(1+2+...+200\right)=5\left(1+2+...+200\right)\)
=>2x-1=5
=>2x=6
=>x=3