Question

chứng minh rằng:

(x+y)\(^2\)- y\(^2\)=x(x+2y)

gíup mk với! ( dùng hằng đẳng thức số 3) mk gấp lắm

Answer 1

\(VT=\left(x+y\right)^2-y^2=\left(x+y-y\right)\left(x+y+y\right)=x\left(x+2y\right)=VP\)

Vậy \(\left(x+y\right)^2-y^2=x\left(x+2y\right)\)

Answer 2

\(VT:\left(x+y\right)^2-y^2=\left(x+y-y\right)\left(x+y+y\right)=x\left(x+2y\right)=VP\left(đpcm\right)\)

Answer 3

Ta có: \(VT=\left(x+y\right)^2-y^2\)

\(=\left(x+y-y\right)\left(x+y+y\right)\)

\(=x\left(x+2y\right)=VP\)

\(\Rightarrowđpcm\)

Answer 4

Ta có:

(x + y)² - y²

= (x + y - y)(x + y + y)

= x(x + 2y) (đpcm)

Vậy (x + y)² - y² = x(x + 2y)