1.(-x+1/2)(-x-1/2)= 2.因式分解:-5a^2+25a= 3.化简求值:[(a-1/2)^2-(a+1/2)^2](a+3),其中a=-2
问题描述:
1.(-x+1/2)(-x-1/2)= 2.因式分解:-5a^2+25a= 3.化简求值:[(a-1/2)^2-(a+1/2)^2](a+3),其中a=-2
答
1.x^2-1/4=2,x^2=2.25,x=+-1.5
2.-5a(a-5)
3.原式=[a^2-a+1/4-(a^2+a+1/4)](a+3)=-2a(a+3)=4*1=4