将y=5000+400X-10X²配方
问题描述：
将y=5000+400X-10X²配方
答
y=5000+400X-10X²
＝-10X²+400X+5000
＝-10(x²-40x-500)
=-10(x²-40x+20²-20²-500)
=-10[(x-20)²-900]
=-10(x-20)²+9000