315.[120-(3x+15)]=7
120-(3x+15)=7:315
120-(3x+15)=\(\frac{1}{45}\)
3x+15 = 120 - \(\frac{1}{45}\)
3x+15=\(\frac{5399}{45}\)
3x=\(\frac{5399}{45}\)-15
3x=\(\frac{4724}{45}\)
x=\(\frac{4724}{45}\) : 3
x=\(\frac{4724}{135}\)
Tình nhanh
625:(35x7-120)
600:(20x6+30)
5x(180-75x2)
125-(315-53x5)
[(5x30+15)-65]:2
[3x[40+15x4)-178]-24
{121-[(24x6+6x76):100+15]}:4+35
{[(175-25x3):25+6]+120}:4+34
128-{[315-(42+58)]:5+57}
[(8x50-356)x3-44]+56
Mong mọi người giúp em
Tìm x biết: 15 + 3 . (120-2x) = 315
315 – 300 : ( x: 15 – 7) = 300
Tìm x
a) 2 . ( x - 2 ) + 7 . ( 3 - x ) = -2 . ( 3x - 18 )
b) ( x - 5 ) + 3 . ( 2 + x ) = 3x + 11
c) 4 . ( x + 2 ) + 15 . ( x + 3 ) = 7 ( x - 9 ) + 120
Tìm x biết: 15 + 3 . (120-2x) = 315
Bài 9: Tính
a) 1 + 7 + 8 + 15 + 23 + …. + 160;
b) 1 + 4 + 5 + 9 + 14 + …. + 60 + 97;
c) 78. 31 + 78. 24 + 78. 17 + 22. 72.
d) (456. 11 + 912). 37 : 13 : 74
e) [(315 + 372). 3 + (372 + 315). 7] : (26. 13 + 74. 14)
Bài 1 tính tổng
a, -1+3-5+7-9+11-13+15-17
b, -6-5-4-3-......-0+1+2+3+4
c, 120-45+318-55-123-315
bài 2 tính
a, 11-12+13-14+15-16+17-18+19-20
b, 101-102-(-103)-104-(-105)-106
c, 12-14+16-18+....+2014-2016
Tìm x biet:
a,5/2x+x=32/15
b,x-7/2x=-32/15
c,-7/3x-7/4x+11/3=18/5
d,-5/6-3x=2/3
e,2x-5/9=-2/3
f,1/2-2/3x=7/12
g,7-|2x-3|=4
h,(19x+2.5^2):14=(13-8)^2-4^2
i,3/4x-2/3=2/7.1/6+5/7.1/6
k,(x+1/2).(2/3-2x)=0
l,x/2013-1/10-1/15-1/21-........-1/120=5/8
A = 1- 4 + 7 -10 +B - .... + 247 - 250
b = 6 - 9 + 12 - 15 + .... - 312 +315
