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a,91-5(5+x)=61
=>25+5x=91-61=30
=>5x=30-25=5
=>x=1
b,\([\left(x+34\right)-50]\)x2=56
=>(x+34)-50=56:2=28
=>x+34=28+50=78
=>x=78-34=44.
c,1045-\([2015-\left(3x-24\right)]\)=5
=>2015-(3x-24)=1045-5=1040
=>3x-24=2015-1040=975
=>3x=975+24=999
=>x=999:3=333
d,\([195-\left(3x-27\right)]\)x39=4212
=>195-(3x-27)=4212:39=108
=>3x-27=195-108=87
=>3x=87+27=117
=>x=39
e,30-3(x-2)=18
=>30-3x+6=18
=>30-3x=18-6=12
=>3x=30-12=18
=>x=18:3=6
a) \(...\Rightarrow5\left(5+x\right)=91-61=30\)
\(\Rightarrow\left(5+x\right)=30:5=6\Rightarrow x=6-5=1\)
b) \(...\Rightarrow\left(x+34\right)-50=56:2=28\)
\(\Rightarrow\left(x+34\right)=28+50=78\Rightarrow x=78-34=44\)
c) \(...\Rightarrow2015-\left(3x-24\right)=1045-5=1040\)
\(\Rightarrow\left(3x-24\right)=2015-1040=975\)
\(\Rightarrow3x=975+24=999\Rightarrow x=999:3=333\)
d) \(...\Rightarrow195-\left(3x-27\right)=4212:39=108\)
\(\Rightarrow\left(3x-27\right)=195-108=87\)
\(\Rightarrow3x=87+27=114\Rightarrow x=114:3=38\)
e) \(...\Rightarrow3\left(x-2\right)=30-18=12\Rightarrow x-2=12:3=4\)
\(\Rightarrow x=4+2=6\)
a) \(1045:\left[215-\left(3x-24\right)\right]=5\)
\(\Rightarrow215-\left(3x-24\right)=1045:5\)
\(\Rightarrow215-\left(3x-24\right)=209\)
\(\Rightarrow3x-24=215-209\)
\(\Rightarrow3x-24=6\)
\(\Rightarrow3x=6+24\)
\(\Rightarrow3x=30\)
\(\Rightarrow x=30:3\)
\(\Rightarrow x=10\)
Vậy x = 10
b) \(\left[195-\left(15x+27\right)\right]\times39=4212\)
\(\Rightarrow195-\left(15x+27\right)=4212:39\)
\(\Rightarrow195-\left(15x+27\right)=108\)
\(\Rightarrow15x+27=195-108\)
\(\Rightarrow15x+27=87\)
\(\Rightarrow15x=87-27\)
\(\Rightarrow15x=60\)
\(\Rightarrow x=60:15\)
\(\Rightarrow x=4\)
Vậy x = 4
_Chúc bạn học tốt_
3:
a: (a-b+c)-(c-b-a)
=a-b+c-c+b+a
=2a
b: \(-\left(a-b\right)+\left(b-c+a\right)-\left(a+b-c\right)\)
\(=-a+b+b-c+a-a-b+c\)
\(=b-a\)
c: \(-\left(a-b-c\right)-\left(-a+b+c\right)-\left(a-b+c\right)\)
\(=-a+b+c+a-b-c-a+b-c\)
\(=-a+b-c\)
2:
a: \(12-\left(-12\right)=12+12=24\)
b: \(-\left(35-49\right)+\left(27-49\right)=-35+49+27-49\)
=-35+27
=-8
c: \(47-\left(59-63\right)+\left(63-47\right)\)
\(=47-59+63+63-47\)
=126-59
=67
d: \(-\left(-20\right)-\left(-30\right)-70\)
=20+30-70
=50-70
=-20
\(5\cdot x+10\cdot9=990\)
\(\Rightarrow5\cdot x+90=990\)
\(\Rightarrow5\cdot x=900\)
\(\Rightarrow x=\dfrac{900}{5}\)
\(\Rightarrow x=180\)
_____________
\(1045:\left[215-\left(3\cdot x-24\right)\right]=5\)
\(\Rightarrow215-\left(3\cdot x-24\right)=1045:5\)
\(\Rightarrow215-\left(3\cdot x-24\right)=209\)
\(\Rightarrow3\cdot x-24=215-209\)
\(\Rightarrow3\cdot x-24=6\)
\(\Rightarrow3\cdot x=30\)
\(\Rightarrow x=10\)
`@` `\text {Ans}`
`\downarrow`
`5.x + 10.9 = 990`
`\Rightarrow 5x + 90 = 990`
`\Rightarrow 5x = 990 - 90`
`\Rightarrow 5x = 900`
`\Rightarrow x = 900 \div 5`
`\Rightarrow x = 180`
Vậy, `x = 180`
\(1045 \div [ 215 - (3 . x - 24 ) ] = 5\)
`\Rightarrow 1045 \div (215 - 3x + 24) = 5`
`\Rightarrow 191 + 3x = 1045 \div 5`
`\Rightarrow 191 + 3x = 209`
`\Rightarrow 3x = 209 - 191`
`\Rightarrow 3x =18`
`\Rightarrow x = 18 \div 3`
`\Rightarrow x = 6`
Vậy, `x = 6.`
\(1734:17=102x17:17=102x1=102\)
\(\left(x-7\right)\)\(2-26=13x17-13x7=13\left(17-7\right)=13x10=130\)
\(\left(x-7\right)2=130+26=156\)
\(x-7=156:2=78\)
\(x=78+7=85\)
\(=>x=85\)
\(195-\left(15x+27\right)=4212:39=108\)
\(15x+27=195-108=87\)
\(15x=87-27=60\)
\(x=60:15=4\)
\(=>x=4\)
- Tính nhẩm
1734 : 17 = 102
- Tìm x
(x - 7) .2 - 26 = 13.17 - 13.7
(x - 7) .2 - 26 = 13.(17 - 7)
(x - 7) .2 - 26 = 13. 10
(x - 7) .2 - 26 = 130
(x - 7) .2 = 130 + 26
(x - 7) .2 = 156
(x - 7) = 156 : 2
(x - 7) = 78
x = 78 + 7
x = 85
___________________
195 - (15x + 27) .39 = 4212 (dấu "[" đặt ở đấu tiên nên không cần thiết)
(15x + 27) .39 = 195 - 4212
(15x + 27) .39 = -4017
(15x + 27) = -4017 : 39
(15x + 27) = -103
15x = -103 -27
15x = -130
x = -130 : 15
x = -26/3
mình biết rồi!giải thế này:nối các số trong tập hợp A với tập hợp B lại,tổng cọng là có 9 phép tính ,rất dễ nhé!
kết quả:M=ngoặc nhọn bên trong ngoặc nhọn là 0;1;2;-1;-2 đóng ngoặc nhọn
a) \(3x-10=2x+13\Leftrightarrow x=13+10=23\)
b) \(x+12=-5-x\Leftrightarrow2x=-17\Leftrightarrow x=-\frac{17}{2}\)
c) \(x+5=10-x\Leftrightarrow2x=5\Leftrightarrow x=\frac{5}{2}\)
d) \(6x+23=2x-12\Leftrightarrow4x=-35\Leftrightarrow x=-\frac{35}{4}\)
e) \(12-x=x+1\Leftrightarrow2x=11\Leftrightarrow x=\frac{11}{2}\)
f) \(14+4x=3x+20\Leftrightarrow x=20-14=6\)
g) \(2\left(x-1\right)+3\left(x-2\right)=x-4\Leftrightarrow2x-2+3x-6=x-4\)
\(\Leftrightarrow5x-8=x-4\Leftrightarrow4x=4\Leftrightarrow x=1\)
h ) \(3\left(4-x\right)-2\left(x-1\right)=x+20\Leftrightarrow12-3x-2x+2=x+20\)
\(\Leftrightarrow14-5x=x+20\Leftrightarrow6x=-6\Leftrightarrow x=-1\)
i ) \(4\left(2x+7\right)-3\left(3x-2\right)=24\Leftrightarrow8x+28-9x+6=24\)
\(\Leftrightarrow34-x=24\Leftrightarrow x=34-24=10\)
k) \(3\left(x-2\right)+2x=10\Leftrightarrow3x-6+2x=5x-6=10\)
\(\Leftrightarrow5x=10+6=16\Leftrightarrow x=\frac{16}{5}\)
Tự KL cho các phần
Câu 1:
A={1;3;5;7;9}
Câu 2:
A. 24 x 82 + 24 x 18 - 100
= 24 x (82 + 18) - 100
= 24 x 100 - 100
= 2400 - 100 = 2300
B.12 + 3 [ 39 - (5 - 2 )2 ]
= 12 + 3. [39 - 32 ]
= 12 + 3 . [39-9]
= 12 + 3.30
= 12 + 90 = 102
\(a.\left[\left(x+34\right)-50\right].2=56\\ \Leftrightarrow\left(x+34\right)-50=28\\ \Leftrightarrow x+34=78\\ \Rightarrow x=44\)
\(b.1045-\left[215-\left(3x-24\right)\right]=5\\ \Leftrightarrow215-\left(3x-24\right)=1040\\ \Leftrightarrow3x-24=-825\\ \Leftrightarrow3x=-801\\ \Rightarrow x=-267\)
\(c.\left[195-\left(15x-27\right)\right].39=4212\\ \Leftrightarrow195-\left(15x-27\right)=108\\ \Leftrightarrow15x-27=87\\ \Leftrightarrow15x=114\\ \Rightarrow x=7,6\)
a) [(x+34)] - 50] . 2 = 56
=x+34-50=56:2
=> x+34-50=28
->x=28+50-34
-> x=44
b,1045 - [ 215 - ( 3x - 24 )] = 5
1045-(215-3x+24)=5
1045-215+3x-24=5
1045-215-24-5=-3x
-> 801=-3x-> x=801:(-3)=-267
,c) [ 195 - ( 15x - 27)] . 39 = 4212
(195-15x+27).39=4212
(195-15x+27)=4212/39=108
195+27-108=15x
114=15x-> x=114/15=7,6
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