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Question
Square of 3x – 4y is ______.
Options
9x2 – 16y2
6x2 – 8y2
9x2 + 16y2 + 24xy
9x2 + 16y2 – 24xy
Solution
Square of 3x – 4y is 9x2 + 16y2 – 24xy.
Explanation:
Square of (3x – 4y) will be (3x – 4y)2.
Comparing (3x – 4y)2 with (a – b)2, we get a = 3x and b = 4y.
Now, using the identity (a – b)2 = a2 – 2ab + b2
(3x – 4y)2 = (3x)2 – 2 · 3x · 4y + (4y)2
= 9x2 – 24xy + 16y2
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