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Use a formula to multiply : i. (x – 5)(x + 5) ii. (2a – 13)(2a + 13) iii. (4z – 5y)(4z + 5y) iv. (2t – 5)(2t + 5) |
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Answer» i. Here, a = x and b = 5 (x – 5)(x + 5) = (x)2 – (5)2 …. [(a + b)(a – b) = a2 – b2] = x2 – 25 ii. Here, A = 2a and B = 13 (2a – 13)(2a + 13) = (2a)2 – (13)2 …. [(A + B)(A – B) = A2 – B2] = 4a2 – 169 iii. Here, a = 4z and b = 5y (4z – 5y)(4z + 5y) = (4z)2 – (5y)2 …. [(a + b)(a – b) = a2 – b2] = 16z2 – 25y2 iv. Here, a = 2t and b = 5 (2t – 5)(2t + 5) = (2t)2 – (5)2 …. [(a + b)(a – b) = a2 – b2] = 4t2 – 25 |
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