已知x=7.21,y=2.79,求1/2x^2+xy+1/2y^2的值

已知x=7.21,y=2.79,求1/2x^2+xy+1/2y^2的值
已知x=7.21,y=2.79,求1/2x^2+xy+1/2y^2的值

已知x=7.21,y=2.79,求1/2x^2+xy+1/2y^2的值
原式=1/2(x²+2xy+y²)
=1/2(x+y)²
=1/2×(7.21+2.79)²
=1/2×10²
=50

1/2x^2+xy+1/2y^2
=1/2(x²+2xy+y²)
=1/2(x+y)²
=1/2×(7.21+2.79)²
=1/2×10²
=50

1/2x^2+xy+1/2y^2
=1/2（x^2+2xy+y^2）
=1/2(x+y)²
=1/2*(7.21+2.79)²
=1/2*100
=50