Question

Bài 1: Phá dấu ngoặc rồi tính:

a)\(\left(a+b+c\right)-\left(a-b+c\right)\)

b)\(\left(4.x+5.y\right)-\left(5.x-4.y-1\right)\)

Bài 2: Chứng minh bất đẳng thức:

a)\(\left(a+b+c+d\right)-\left(a-b-c+d\right)+1=a-\left(a-2b-2c-d\right)+\left(d+1\right)\)

b)\(\left(4x-3y+2\right)-\left(3x-4y+2\right)=\left(2x+2y\right)-\left(x+y\right)\)

Answer 1

Bài 1: Phá dấu ngoặc rồi tính:

a. \(\left(a+b+c\right)-\left(a-b+c\right)\)

\(=a+b+c-a+b-c\)

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

\(=2b\)

b. \(\left(4x+5y\right)-\left(5x-4y-1\right)\)

\(=4x+5y-5x+4y+1\)

\(=\left(4x-5x\right)+\left(5y+4y\right)+1\)

\(=-x+9y+1\)