Đáp án:
`22)(a+b)^2-4=(a+b-2)(a+b+2)`
`23)(a-2b)^2-4b^2=(a-2b-2b)(a-2b+2b)`=(a-4b)a`
`24)(a+3b)^2-9b^2=(a+3b-3b)(a+3b+3b)=a(a+6b)`
`25)(a-5b)^2-16b^2=(a-5b-4b)(a-5b+4b)=(a-9b)(a-b)`
`26)25a^2-(a-b)^2=(5a-a+b)(5a+a-b)=(4a+b)(6a-b)`
`27)4a^2-(a+b)^2=(2a-a-b)(2a+a+b)=(a-b)(3a+b)`
`28)49a^2-(2a-b)^2=(7a-2a+b)(7a+2a-b)=(5a+b)(9a-b)`
`29)36a^2-(3a-2b)^2=(6a-3a+2b)(6a+3a-2b)=(3a+2b)(9a-2b)`
`30)81a^2-(5a-3b)^2=(9a-5a+3b)(9a+5a-3b)=(4a+3b)(14a-3b)`
`31)(a-2b)^2-(3a+b)^2=(a-2b-3a-b)(a-2b+3a+b)=(-4a-3b)(4a-b)`
`32)(5a-b)^2-(2a+3b)^2=(5a-b-2a-3b)(5a-b+2a+3b)=(3a-4b)(7a+2b)`
`33)(4a+3b)^2-(b-2a)^2`
`=(4a+3b-b+2a)(4a+3b+b-2a)`
`=(6a+2b)(2a+4b)`
`=4(3a+b)(a+2b)`
`34)(2a-b)^2-4(a-b)^2`
`=[2a-b-2(a-b)][2a-b+2(a-b)]`
`=(2a-b-2a+2b)(2a-b+2a-2b)`
`=b(4a-3b)`
`35)9(a+b)^2-4(a-2b)^2`
`=[3(a+b)-2(a-2b)][3(a+b)+2(a-2b)]`
`=(3a+3b-2a+4a)(3a+3b+2a-4b)`
`=(a+7b)(5a-b)`
`36)4(2a-b)^2-16(a-b)^2`
`=[2(2a-b)-4(a-b)][2(2a-b)+4(a-b)]`
`=(4a-2b-4a+4b)(4a-2b+4a-4b)`
`=2b(8a-6b)`
`=4b(4a-3b)`
`37)25(x-3)^2-(2x-7)^2`
`=[5(x-3)-(2x-7)][5(x-3)+(2x-7)]`
`=(5x-15-2x+7)(5x-15+2x-7)`
`=(3x-8)(7x-22)`
`38)49(x-5)^2-(x+4)^2`
`=[7(x-5)-(x+4)][7(x-5)+(x+4)]`
`=(7x-35-x-4)(7x-35+x+4)`
`=(6x-39)(8x-31)`
`=3(2x-13)(8x-31)`
`39)81(x+7)^2-(3x+8)^2`
`=[9(x+7)-(3x+8)][9(x+7)+(3x+8)]`
`=(9x+63-3x-8)(9x+63+3x+8)`
`=(6x+55)(12x+71)`
`40)36(x-y)-25(2x-1)^2`
-(ko phân tích đc)-
