Question

using a suitable identity, find the product of the following (5x-9y) 2

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Answer 1

Answer:

(5x-9y)²

Using the identity:-(a-b)²=a²-2ab+b²

a=5x, b=9y

=(5x)²-2(5x)(9y)+(9y)²

=25x²-90xy+81y²

Answer 2

$= ( {5x - 9y)}^{2}$

$= (a - b) ^{2} = {a}^{2} + {b}^{2} - 2ab$

$= {5x}^{2} + {9y}^{2} - 2 \times 5x \times 9y$

$= {25x}^{2} + {81y}^{2} - 90xy$