Tìm x biết
a) x +(x + 1) + (x + 2) + .... + (x +30) = 620
b) 2+4+6+8+....+2x = 210
c) (x-1) +(x-2)+(x-3)+...+(x-20) = -610
d) (x-3)(2x-7) = 0
e) |3-x| = x-5
g) |5x-2| \(^{_{ }\le}\)13
h) x+|2-x|=6
t) \(3^x+3^{x+1}+3^{x+2}=1053\)
i) | x+1| +|x-2| = 3
Nhanh lên! Mình cần gấp. Nguyễn Huy Tú