2[x+y]²-9[x+y]-5 Factorise....
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Answered by
37
let x+y=a
2a^2-9a-5=2a^2+1a-10a-5
=a(2a+1)-5(2a+1)
=(a-5)(2a+1)
=(x+y-5)(2x+2y+1)
2a^2-9a-5=2a^2+1a-10a-5
=a(2a+1)-5(2a+1)
=(a-5)(2a+1)
=(x+y-5)(2x+2y+1)
Answered by
50
Now, 2 (x + y)² - 9 (x + y) - 5
= 2 (x + y)² - (10 - 1) (x + y) - 5
= 2 (x + y)² - 10 (x + y) + (x + y) - 5
= 2 (x + y) (x + y - 5) + 1 (x + y - 5)
= (x + y - 5) {2 (x + y) + 1)
= (x + y - 5) (2x + 2y + 1),
which is the required factorization.
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