(1)
锛坹+2)(y+4)+1
=y^2+6y+8+1
=y^2+6y+9
=(y+3)^2
(2)
(2a+1)(2a-1)+(a-2)²-4锛坅+1)(a-2)
= 4a^2 -1 +a^2-4a+4 - 4a^2+4a+8
=a^2+11
璁$畻缁撴灉鍜 a^2鏈夊叧涓攢锛屾墍浠ュ綋a=2鎴栬卆=-2鏃讹紝缁撴灉閮芥槸 15锛屾槸甯嗗弸涓鏍风殑銆
(3)璁綼=3.456锛屽垯鍗栬娇娓
鍘熷紡
=a(a-1)(a+2) - a^3 -(a-2)^2
=a^3+a^2-2a -a^3 - a^2+4a-4
=2a-4
=2(a-2)
鎶 a = 3.456浠e叆锛屽緱
鍘熷紡
= 2(3.456-2)
=2*1.456
=2.912
鑷繁鎯冲惂
0鎮祻鍒嗭紝鎴戞墠涓嶅府浣犮