Câu 1:
h) 135.(171 – 123) – 171.(135 - 123)
= 135.171 - 135.123 - 171.135 + 171.123
= (135.171 - 171.135) - (135.123 - 171.123)
= 0 - 123.(135 - 171)
= -123.(-36)
= 4428
Câu 2:
a) -2x – (x – 17) = 34 – (-x + 25)
-2x - x + 17 = 34 + x - 25
-2x - x - x = 34 - 25 - 17
-4x = -8
x = (-8) : (-4)
x = 2
Vậy x = 2
b) 17x – (-16x – 37) = 2x + 43
17x + 16x + 37 = 2x + 43
17x + 16x - 2x = 43 - 37
31x = 6
x = 6/31
Vậy x = 6/31
c) -2x – 3.(x – 17) = 34 – 2(-x + 25)
-2x - 3x + 51 = 34 + 2x - 50
-2x - 3x - 2x = 34 - 50 - 51
-7x = -67
x = 67/7
Vậy x = 67/7
d) 17x + 3.(-16x – 37) = 2x + 43 - 4x
17x - 48x - 111 = 2x + 43 - 4x
17x - 48x - 2x + 4x = 43 + 111
-29x = 154
x = -154/29
Vậy x = -154/29