Bài 29 trang 40 SGK Toán 7 tập 2

Tính:a) \((x + y) + (x - y)\);b) \((x + y) - (x - y)\).

Lời giải

a) \((x + y) + (x - y) = x + y + x - y \)\(\,=(x + x) + (y - y) = 2x\);

b) \((x + y) - (x - y) = x + y - x + y \)\(\,= (x - x) + (y + y) = 2y\).


Quote Of The Day

“Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.”