1. 2(x+3)^2=2x^2+12x+18
2. x^2-5(x-2)=x(x-10)
3. (x+1)(x-6)+x(x-5)=2(x-3)^2
maths for f.2
2008-10-10 12:16 am
回答 (1)
2008-10-10 1:02 am
✔ 最佳答案
1. 2(x + 3)2 = 2x2 + 12x + 18
2(x2 + 6x + 9) = 2x2 + 12x + 18
2x2 + 12x + 18= 2x2 + 12x + 18
For any value of x, LHS = RHS.
It is an identity.
LHS
= 2(x + 3)2
= 2(x2 + 6x + 9)
= 2x2 + 12x + 18
= RHS
=====
2.
x2 - 5(x - 2) = x(x - 10)
x2 - 5x + 10 = x2 - 10x
5x = -10
x = -2
=====
3.
(x + 1)(x - 6) + x(x - 5) = 2(x - 3)2
(x2 - 5x - 6) + (x2 - 5x) = 2(x2 - 6x + 9)
x2 - 5x - 6 + x2 - 5x = 2x2 - 12x + 18
2x = 24
x = 12
=
收錄日期: 2021-04-23 23:08:24
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