分解因式:(1)99²+198+1(2)当x=3.6,y=6.4时,求代数式1/4x²+1/2xy+1/4y²的值
问题描述:
分解因式:(1)99²+198+1(2)当x=3.6,y=6.4时,求代数式1/4x²+1/2xy+1/4y²的值
答
99²+198+1=99²+2×99+1²=(99+1)²=100²=10000(1/4)x²+(1/2)xy+(1/4)y²=(1/4)[x²+2xy+y²]=(1/4)(x+y)²以x=3.6、y=6.4代入,得:原式=(1/4)×(3.6+6.4)...