Question

Thu gọn biểu thức sau :

a) a - b + c - (a - b + c) + 3b

b) - (2a - b) - (b + 3a)

c) a(b + c) - b(a - c)

Answer 1

a) a - b + c - (a - b + c) + 3b

= a - b + c - a + b - c +3b

= 3b

b) - (2a - b) - (b + 3a)

= -2a + b - b - 3a

= -5a

c) a(b + c) - b(a - c)

= ab + ac - ab + bc

= ac + bc

Answer 2

\(a,a-b+c-\left(a-b+c\right)+3b=a-b+c-a+b-c+3b\)

\(=3b\)

\(b,-\left(2a-b\right)-\left(b+3a\right)=-2a+b-b-3a=-5a\)

\(c,a\left(b+c\right)-b\left(a-c\right)=ab+ac-ab+bc=ac+bc\)

Answer 3

a) a - b + c - (a - b + c) + 3b

=a - b + c - a + b - c + 3b

=3b

b) - (2a - b)-(b + 3a)

=-2a-b-b-3a

=-5a-2b

c) a(b+c) - b(a-c)

=ab+ac-ba+bc

=ac+bc

=(a+b)c