已知m²-4m+n²+8n+20=0,求方程mx²-nx+2=0的解
问题描述:
已知m²-4m+n²+8n+20=0,求方程mx²-nx+2=0的解
答
m²-4m+n²+8n+20=0(m²-4m+4)+(n²+8n+16)=0(m-2)²+(n+4)²=0m-2=0 n+4=0m=2 n= -4mx²-nx+2=02x²+4x+2=0x²+2x+1=0(x+1)²=0x1=x2= -1(80+2x)(50+2x)=5400 解下(80+2x)(50+2x)=54004000+260x+4x²-5400=0x²+65x-350=0(x+70)(x-5)=0x1= -70x2=5某种品牌的手机经过 四。五月份连续两次降价,每部售价由1000元降价到810元,求平均每月降价的百分率你的问题太多,先采纳,然后再求助吧