Hỏi cho vui thui chán quá :)))
Bài 1:Tìm x
a) 5x - 16 = 40 + x e) 2 (x -5) - 3 (x + 7) = 14
b) 4x - 10 = 15 - x g) 5 (x - 6) - 2 (x + 3) = 12
c) -12 + x = 5x - 20 h) -3 (x - 5) + 6 (x + 2)= 9
d) x + 15 = 7 - 6x i) 10 (x - 7) - 8 (x + 5) = 6 . (-5) + 24
Bài 2:Tính các tổng sau:
a) A = 1-2+3-4+5-6+7-8+..............+2005-2006
b) B = 1-3+5-7+..................+2021-2023
c) C = 2-4+6-8+...............+2008-2010
Bài 3; Tìm x biết:
(x + 1) + (x + 2) + (x + 3) + .......................(x +1000) = 5750
ai xong đầu tiên cho tick free nè :)))
5\(x\) - 16 = 40 + \(x\)
5\(x\) - \(x\) = 40 + 16
4\(x\) = 56
\(x=56:4\)
\(x=14\)
Vậy \(x=14\)
b; 4\(x\) - 10 = 15 - \(x\)
4\(x\) + \(x\) = 15 +10
5\(x=25\)
\(x=25:5\)
\(x=5\)
Vậy \(x=5\)
c; -12 + \(x\) = 5\(x-20\)
5\(x\) = - 12 + \(x\) + 20
5\(x\) - \(x\) = - 12+ 20
4\(x\) = 8
\(x=\dfrac{8}{4}\)
\(x=2\)
Vậy \(x=2\)
d; \(x+15\) = 7 - 6\(x\)
6\(x\) = 7 - \(x\) - 15
6\(x\) + \(x\) = 7 - 15
7\(x\) = - 8
\(x=-\dfrac{8}{7}\)
Vậy \(x=-\dfrac{8}{7}\)