Question

factorise the following algebraic expressions.
using this identity = (a+b)(a-b)​

Answer 1

Answer:

20. 4(x-y)²-(x+y)²

= (4×x) -(4×y) - (x×x)+(y×y)

= (4x×4x )-(4y×4y) 1x+1y

= 16x-16y-1x+1y

= 16x+1x - 16y-1y

ans.= 17x-15y

21. 9(x+y)²-16(x-y)²

= (9×x)+(9×y)-(16×x)-(16×y)

= 9x+9y-16x-16y

= (9x×9x) +(9y×9y) - (16x×16x) -(16y×16y)

= 81x+81y -256x-256y

= 81x+256x-256y-81y

ans.= 337x - 175y

23. 4x²+12xy+9y²-z²

= (4x×4x) + 12xy + (9y×9y) -(z×z)

= 16x+12xy+81y-1z

ans. = 16x+12xy+81y-1z

24. 25-a²-2ab-b²

= 25-(a×a) -2ab -(b×b)

ans.= 25-1a-2ab-1b

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