Question:
Square of 3x – 4y is
(a) 9x2 – 16y2
(b) 6x2 – 8y2
(c) 9x2 + 16y2 + 24xy
(d) 9x2 + 16y2 – 24xy
Solution:
(d) 9x2 + 16y2 – 24xy
As per the condition in the question, (3x – 4y)2
The standard identity = (a – b)2 = a2 – 2ab + b2
Where, a = 3x, b = 4y
Then,
(3x – 4y)2 = (3x)2 – (2 × 3x × 4y) + (4y)2
= 9x2 – 24xy + 16y2
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