Rút gọn biểu thức
a, (x + y)^2 + (x – y)^2
b, 2(x – y)(x + y) + (x + y)^2 + (x – y)^2
c, (x – y + z)^2 + (z – y)^2 + 2(x – y + z)(y – z)
Rút gọn biểu thức a, (x + y)^2 + (x – y)^2 b, 2(x – y)(x + y) + (x + y)^2 + (x – y)^2 c, (x – y + z)^2 + (z – y)^2 + 2(x – y + z)(y – z)
By Alice
a, (x+y)² + (x–y)²
= (x²+2xy+y²)+(x²-2xy+y²)
= x²+2xy+y²+x²-2xy+y²
= 2x²+2y²
= 2(x²+y²)
b, 2(x–y).(x+y)+(x+y)²+(x–y)²
= 2(x²-y²)+2(x²+y²)
= 2x²-2y²+2x²+2y²
= 4x²
c, (x–y+z)²+(z–y)²+2(x–y+z).(y–z)
= (x–y+z)²– 2(x-y+z)(z-y)+(z-y)²
= (x−y+z−z+y)²
= x²
a; ( x+y)^2+(x-y)^2
=>x^2+2xy+y^2+x^2-2xy+y^2
=>2x^2+2y^2
=>2(x^2+y^2)
b;2(x-y)(x+y)+(x+y)^2+(x-y)^2
=>2(x^2-y^2)+2(x^2+y^2)
=>2x^2-2y^2+2x^2+2y^2
=>4x^2
c;=>x^2-y^2+z^2+z^2-2zy+y^2+2x-2y+2zy-2z^2
=>x^2 -2x+2y
câu c mk ko chắc lắm ^^
#chúc bn học tốt