【参考答案】
①x²-4x-5
=(x²-4x+4)-4-5
=(x-2)²-9
②x²-7x-10
=x²-7x+(7/2)²-(7/2)²-10
=[x-(7/2)]²-(49/4)-(40/4)
=[x-(7/2)]²-(89/4)
有不理解的地方欢迎追问.
请问数学中如何配方,例如x^2-4x-5 x^2-7x-10
【参考答案】
①x²-4x-5
=(x²-4x+4)-4-5
=(x-2)²-9
②x²-7x-10
=x²-7x+(7/2)²-(7/2)²-10
=[x-(7/2)]²-(49/4)-(40/4)
=[x-(7/2)]²-(89/4)
有不理解的地方欢迎追问.