4.-(a+1)²+9(a-2)²刚才的提问已经被百度吞掉了

4.-(a+1)²+9(a-2)²刚才的提问已经被百度吞掉了
4.-(a+1)²+9(a-2)²
刚才的提问已经被百度吞掉了

4.-(a+1)²+9(a-2)²刚才的提问已经被百度吞掉了

-(a+1)²+9(a-2)²
=9(a-2)²-(a+1)²
=[3(a-2)+(a+1)][3(a-2)-(a+1)]
=[3a-6+a+1][3a-6-a-1]
=(4a-5)(2a-7)

原式=9（a-2）^2-(a+1)^2
=(3a-6)^2-(a+1)^2
=(3a-6+a+1)(3a-6-a-1)
=(4a-5)(2a-7)

-(a+1)²+9(a-2)²
=9(a-2)²-(a+1)²
=（3a-6)²-(a+1)² 9=3²
=(3a-6+a+1)(3a-6-a-1) 平方差
=(4a-5)(2a-7)

4-（a平方+2a+1）+9(a平方-4a+4）
=4-a平方-2a-1+9a平方-36a+36
=8a平方-38a+39