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a)96-3(x+8)=42
3(x+8)=96-42
3(x+8)=54
x+8=54:3
x+8=18
x=18-8
x=10
b)36:(x-5)=2^
36:(x-5)=4
(x-5)=36:4
x-5=9
x=9+5
x=14
c)15.5(x-35)-525=0
75(x-35)=0+525
x-35=525:75
x-35=7
x=7+35
x=42
d)[3.(70-x)+5]:2=46
3.(70-x)+5=46x2
3.(70-x)+5=92
3.(70-x)=92-5
3.(70-x)=87
70-x=87:3
70-x=29
x=70-29
x=41
HT
\(\left(2x+1\right):7=2^2+3^2 \)
\(\Leftrightarrow\left(2x+1\right):7=13\)
\(\Leftrightarrow2x+1=13.7\)
\(\Leftrightarrow2x+1=91\)
\(\Leftrightarrow2x=90\)
\(\Leftrightarrow x=45\)
\(400-x.3=100\)
\(\Leftrightarrow-x.3=400-100\)
\(\Leftrightarrow-x.3=300\)
\(\Leftrightarrow-x=300:3\)
\(\Leftrightarrow x=100\)
\(96-3\left(x+8\right)=42\)
\(\Leftrightarrow3\left(x+8\right)=96-42\)
\(\Leftrightarrow3\left(x+8\right)=54\)
\(\Leftrightarrow x+8=54:3\)
\(\Leftrightarrow x+8=18\)
\(\Leftrightarrow x=10\)
\(15.5\left(x-35\right)-525=0\)
\(\Leftrightarrow75\left(x-35\right)-525=0\)
\(\Leftrightarrow75\left(x-35\right)=525\)
\(\Leftrightarrow75x-2625=525\)
\(\Leftrightarrow75x=525+5625\)
\(\Leftrightarrow75x=3150\)
\(\Leftrightarrow x=42\)
- Chúc bạn làm bài tốt !
(x+74) - 318=200
x+74 =200+318
x+74 =518
x =518-74
x = 444
[ (x-29) - 11 ] : 2 = 8
[ (x-29) - 11 ] = 8x2
[ (x-29) - 11 ] = 16
x-29 = 16 + 11
x-29 = 27
x = 27 + 29
x = 56
3636 : (12x -91) =36
12x-91 =3636 : 36
12x-91 = 101
12x = 101 + 91
12x = 192
x = 192 : 12
x = 16
[ ( 250 - 25 ) : 15 ] : x = ( 450 - 60 ) : 130
[ 225 : 15 ] : x = 390 : 130
15 : x = 3
x = 15 : 3
x = 5
[ ( 4x + 28 ) . 3 - 55 ] : 5 = 35
[ ( 4x + 28 ) . 3 - 55 ] = 35 : 5
[ ( 4x + 28 ) . 3 - 55 ] = 7
( 4x + 28 ) . 3 = 7 + 55
( 4x + 28 ) . 3 = 62
( 4x + 28 ) = 62 : 3
SAI ĐỀ RỒI TÍNH KO RA
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
1) ( x - 2 ) . ( x + 15 ) = 0
\(\Rightarrow\) x - 2 = 0 hoặc x + 15 = 0
* Nếu x - 2 = 0
x = 0 + 2
x = 2
* Nếu x + 15 = 0
x = 0 - 15
x = -15
Vậy x \(\in\) { 2 ; -15 }
2) ( 7 - x ) . ( x + 19 ) = 0
\(\Rightarrow\) 7 - x = 0 hoặc x + 19 = 0
* Nếu 7 - x = 0
x = 7 - 0
x = 7
* Nếu x + 19 = 0
x = 0 - 19
x = -19
Vậy x \(\in\) {7 ; -19}
\(a,96-3\left(x+8\right)=42\\ \Rightarrow3\left(x+8\right)=54\\ \Rightarrow x+8=18\\ \Rightarrow x=10.\\ b,15.5\left(x-25\right)-225=0\\ \Rightarrow75\left(x-25\right)-225=0\\ \Rightarrow75\left(x-25\right)=225\\ \Rightarrow x-25=3\\ \Rightarrow x=28.\\ c,250:x+15=25\\ \Rightarrow250:x=10\\ \Rightarrow x=25\\ d,36:\left(x-5\right)=2^2\\ \Rightarrow36:\left(x-5\right)=4\\ \Rightarrow x-5=9\\ \Rightarrow x=14.\\ e,\left[3.\left(70-x\right)+5\right]:2=46\\ \Rightarrow3.\left(70-x\right)+5=92\\ \Rightarrow3\left(70-x\right)=87\\ \Rightarrow70-x=29\\ \Rightarrow x=41.\)