Question

phân tích thành nhân tử

`25a^2 -(a-b)^2`

`4a^2 -(a+b)^2`

`49a^2 -(2a-b)^2`

`36a^2-(3a-2b)^2`

`81a^2 -(5a-3b)^2`

Answer 1

a: =(5a-a+b)(5a+a-b)

=(4a+b)(5a-b)

 

b: =(2a-a-b)(2a+a+b)

=(a-b)(3a+b)

c: =(7a-2a+b)(7a+2a-b)

=(5a+b)(9a-b)

d: =(6a-3a+2b)(6a+3a-2b)

=(3a+2b)(9a-2b)

e: =(9a-5a+3b)(9a+5a-3b)

=(4a+3b)(14a-3b)

Answer 2

Lời giải:

$25a^2-(a-b)^2=(5a)^2-(a-b)^2=[5a-(a-b)][5a+(a-b)]=(4a+b)(6a-b)$

$4a^2-(a+b)^2=(2a)^2-(a+b)^2=[2a-(a+b)][2a+(a+b)]=(a-b)(3a+b)$

$49a^2-(2a-b)^2=(7a)^2-(2a-b)^2=[7a-(2a-b)][7a+(2a-b)]=(5a+b)(9a-b)$

$36a^2-(3a-2b)^2=(6a)^2-(3a-2b)^2=[6a-(3a-2b)][6a+(3a-2b)]$

$=(3a+2b)(9a-2b)$

$81a^2-(5a-3b)^2=(9a)^2-(5a-3b)^2=[9a-(5a-3b)][9a+(5a-3b)]$

$=(4a+3b)(14a-3b)$