已知实数x,y,满足x²+y²-2x+4y+5=0,试求x,y的值 已知x(x+1)(x+2)(x+3)+1=25求x²+3x的值
问题描述:
已知实数x,y,满足x²+y²-2x+4y+5=0,试求x,y的值 已知x(x+1)(x+2)(x+3)+1=25求x²+3x的值
答
x^2+y^2-2x+4y+5=0x^2-2x+1+y^2+4y+4=0(x-1)^2+(y+2)^2=0(x-1)^2=0.(y+2)^2=0x=1,y=-2x(x+1)(x+2)(x+3)+1=25x(x+1)(x+2)(x+3)-24=0x(x+3)(x+1)(x+2)-24=0(x^2+3x)(x^2+3x+2)-24=0(x^2+3x)^2+2(x^2+3x)-24=0(x^2+3x...(2x-1)²=16(x+2)²求x 。怎么做。(2x-1)²=16(x+2)² (2x-1)²-16(x+2)² =0[(2x-1)-4(x+2)] [(2x-1)+4(x+2)] =0(2x-1-4x-8)(2x-1+4x+8) =0(-2x-9)(6x+7) =0(2x+9)(6x+7) =0x=-9/2或x=-7/6