`#Sad`
`a)`
`(3x+5)^2`
`= 9x^2+30x+25`
`b)`
`(6x^2+(1)/(3)x^2)^2`
`= 36x^4+4x^4+(1)/(9)x^4`
`= (361)/(9)x^4`
`c)`
`(5x-4y)^2`
`= 25x^2-40xy+16y^2`
`d)`
`(2x^2y-3y^3x)^2`
`= 4x^4y^2-12x^3y^4+9x^2y^6`
`e)`
`(5x-3)(5x+3)`
`= 25x^2-9`
`f)`
`(6x+5y)(6x-5y)`
`= 36x^2-25y^2`
`g)`
`(-4xy-5)(5-4xy)`
`= (-5-4xy)(5-4xy)`
`= -(5+4xy)(5-4xy)`
`= -(25-16x^2y^2)`
`= -25+16x^2y^2`
`= 16x^2y^2-25`
`h)`
`(a^2b+ab^2)(ab^2-a^2b)`
`= (ab^2+a^2b)(ab^2-a^2b)`
`= a^2b^4-a^4b^2`
`i)`
`(3x-4)^2+2.(3x-4)(4-x)+(4-x)^2`
`= (3x-4+4-x)^2`
`= 4x^2`
`j)`
`(3a-1)^2+2.(9a^2-1)+(3a+1)^2`
`= (3a-1)^2+2.(3a-1)(3a+1)+(3a+1)^2`
`= (3a-1+3a+1)^2`
`= (6a)^2`
`= 36a^2`
`k)`
`(a^2+ab+b^2)(a^2-ab+b^2)-(a^4+b^4)`
`= a^4-a^3b+a^2b^2+a^3b-a^2b^2+ab^3+a^2b^2-ab^3+b^4-a^4-b^4`
`= (a^4-a^4)+(b^4-b^4)+(-a^3b+a^3b)+(a^2b^2-a^2b^2+a^2b^2)+(ab^3-ab^3)`
`= a^2b^2`
