bai 1 :Bo dau ngoac roi thu gon bieu thuc: a, A= (a+b) - (a-b) + (a-c) - (a+b) b, B= (a+b-c) + (a-b+c) - (b+c-a) - (a-b-c)bai 2: tim \(x\in z\), bieta, -5x-(-3)=13 ; b, 15-(x-7) =-21 ; c, 3x+17=2 d, -12 (x-5)+7(3-x)=5 ; e, \(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\) ;...
Đọc tiếp
bai 1 :Bo dau ngoac roi thu gon bieu thuc:
a, A= (a+b) - (a-b) + (a-c) - (a+b) b, B= (a+b-c) + (a-b+c) - (b+c-a) - (a-b-c)
bai 2: tim \(x\in z\), biet
a, -5x-(-3)=13 ; b, 15-(x-7) =-21 ; c, 3x+17=2 d, -12 (x-5)+7(3-x)=5 ; e, \(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\) ; f, \(\frac{2}{5}+\frac{3}{5}.\left(3x-3,7\right)=-\frac{53}{10}\)
a) -5x - (-3) = 13
=> -5x + 3 = 13
=> -5x = 13 - 3
=> -5x = 10
=> x = 10 : (-5)
=> x = -2
b) 15 - (x - 7) = -21
=> 15 - x + 7 = -21
=> (15 + 7) - x = -21
=> 22 - x = -21
=> x = 22 - (-21)
=> x = 43