(1)计算:(x+3)2-(x-1)(x-2)(2)化简:x2+2xx2-4-2x-2(3)解方程:x2-2x-3=0-数学

题目简介

(1)计算:(x+3)2-(x-1)(x-2)(2)化简:x2+2xx2-4-2x-2(3)解方程:x2-2x-3=0-数学

题目详情

(1)计算:(x+3)2-(x-1)(x-2)
(2)化简:
x2+2x
x2-4
-
2
x-2

(3)解方程:x2-2x-3=0
题型:解答题难度:中档来源:不详

答案


(1)(x+3)2-(x-1)(x-2)
=x2+6x+9-(x2-3x+2)
=x2+6x+9-x2+3x-2
=9x+7.
(2)
x2+2x
x2-4
-class="stub"2
x-2

=
x(x+2)
(x+2)(x-2)
-class="stub"2
x-2

=class="stub"x
x-2
-class="stub"2
x-2

=1.
(3)移项,得x2-2x=3,配方,
得(x-1)2=4,
∴x-1=±2,
∴x1=-1,x2=3.

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