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a) 150 : [17 - (2x - 3)] = 350
=> 17 - (2x - 3) = \(\frac{150}{350}=\frac{3}{7}\)
=> 2x - 3 = \(17-\frac{3}{7}=\frac{116}{7}\)
=> 2x = \(\frac{116}{7}+3\)
=> 2x = \(\frac{137}{7}\)
=> x = \(\frac{137}{7}:2=\frac{137}{14}\)
b) 4 . [105 - (x - 9)] - 486 = 0
=> 4. [105 - (x - 9)] = 486
=> 105 - (x - 9) = 243/2
=> x - 9 = \(105-\frac{243}{2}=-\frac{33}{2}\)
=> x = \(-\frac{33}{2}+9=-\frac{15}{2}\)
c) 1000 - 2{600 - 4.[198 - 7.(21 - 7)]}.x = 200
=> 1000 - 2{600 - 4.[198 - 7.14]}.x = 200
=> 1000 - 2{600 - 4.[198 - 98].x = 200
=> 1000 - 2{600 - 4.100}.x = 200
=> 1000 - 2{600 -400}.x = 200
=> 1000 - 2.200.x = 200
=> 2.200.x = 800
=> 400.x = 800
=> x = 2
Câu 2 :
a) 350 : [19 - (7x - 3)] = 350
=> 19 - (7x - 3) = 1
=> 7x - 3 = 18
=> 7x = 21
=> x = 3
b) 7.[109 - (x - 9)] - 420 = 0
=> 7.[109 - (x - 9)] = 420
=> 109 - (x - 9) = 60
=> x - 9 = 49
=> x = 49 + 9 = 58
c) 254 - 2{200 - 4.[90 - 7.(19 - 9)]}.x = 54
=> 254 - 2{200 - 4.[90 - 7.10]}.x = 54
=> 254 - 2{200 - 4[90 - 70]} . x= 54
=> 254 - 2{200 - 4.20} . x = 54
=> 254 - 2{200 - 80}.x = 54
=> 254 - 2.120 . x= 54
=> 2.120.x = 200
=> 240.x = 200
=> \(x=\frac{5}{6}\)
1b)\(\frac{7}{19}x\frac{8}{11}+\frac{3}{11}:\frac{19}{7}-\frac{2}{-19}=\frac{7}{19}x\frac{8}{11}+\frac{3}{11}x\frac{7}{19}+\frac{2}{19}=\left(\frac{8}{11}+\frac{3}{11}\right)\frac{7}{19}+\frac{2}{19}=\frac{7}{19}+\frac{2}{19}=\frac{9}{19}\)
c)\(4\left(\frac{4}{9}+\frac{7}{11}-\frac{4}{9}\right)=4\frac{7}{11}\)
từ rồi làm tiếp
a) 350 - 6(x - 2) = 230
6(x - 2) = 350 - 230
6(x - 2) = 120
x - 2 = 120 : 6
x - 2 = 20
x = 20 + 2
x = 22
a) (519:517+3):7
=(52+3):7
=(25+3):7
=28:7
=4
b) 79:77–32+23.52
=72–9+8.25
=49–9+8.25
=48+200
=248
c) 1200:2+62.21+18
=600+36.2+18
=600+72+18
=690
d) 59.57+12.3+70
=516+36+1
=516+37
=...
2.
a) 200–(2x+6)=43
200–(2x+6)=64
2x+6=200–64
2x+6=136
2x=136–6
2x=130
x=130:2
x=65
b) 2x—72=5–32
2x—49=5–9
2x—49=—4
2x=-4+49
2x=45
x=45:2
x=22,5
c) 4.(x+41)=22.102
.......
3.
Ta có: Để 199* chia hết cho 2
Thì 199* là số chẵn
==> * € {0;2;4;6;8}
Do đó: 199*=1990;1992;1994;1996;1998
Mà 199* chia hết cho 3
Nên 199*€{1992;1998}
Vậy các số cần tìm là 1992;1998
a , 6x + x=5¹¹ : 5⁹ + 3¹
7x= 5²+ 3¹
7x = 25+3
7x = 28
x = 4
x(x+2)=0
suy ra x=0 hoặc x+2=0
5-2x=-7
2x=-7+5
2x=-(7-5)
2x=-2
x=-2:2
x=-1
Vậy x=-1
NHỚ TÍCH MK NHA
Tự học giúp bạn có được một gia tài
Jim Rohn – Triết lý cuộc đời
\(\text{a)}350:\left[19-\left(7x-3\right)\right]=350\)
\(\Rightarrow19-\left(7x-3\right)=1\)
\(\Rightarrow19-7x+3=1\)
\(\Rightarrow-7x=-21\)
\(\Rightarrow x=3\)
\(\text{b)}7.\left[109-\left(x-9\right)\right]-420=0\)
\(\Rightarrow7\left(109-x+9\right)=420\)
\(\Rightarrow118-x=60\)
\(\Rightarrow x=58\)
\(\text{c)}252-2\left\{200-4\left[90-7.\left(19-9\right)\right]\right\}.x=4\)
\(\Rightarrow2\left\{200-4\left[90-7.10\right]\right\}.x=250\)
\(\Rightarrow\left[200-4\left(90-70\right)\right].x=125\)
\(\Rightarrow\left[200-4.20\right].x=125\)
\(\Rightarrow120x=125\)
\(\Rightarrow x=\frac{125}{120}=\frac{25}{24}\)
\(\text{Xin điểm ạ}\)
350:[19-(7x-3)]=350
[19-(7x-3)]=350:350
[19-(7x-3)]=1
(7x-3)=19-1
(7x-3)=18
7x=18+3
7x=21
x=21:7
x=3
vậy x=3
7.[109-(x-19)]-420=0
7.[109-(x-19)]=0+420
7.[109-(x-19)]=420
[109-(x-19)]=420:7
[109-(x-19)]=60
(x-19)=109-60
(x-19)=49
x=49+19
x=58
vậy x=58
254-2{200-4.[90-7.(19-9)]}.x=4
254-2{200-4.[90-7.10]}.x=4
254-2{200-4.[90-70]}.x=4
254-2{200-4.20}.x=4
254-2{200-80}.x=4
254-2.120.x=4
254-240.x=4
240.x=254-4
240.x=250
x=250:240
x=25/24
vậy x=25/24