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Find the value of 31^2-19 using the propety |
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Answer» Answer: Question 1: USING APPROPRIATE PROPERTIES, find: (i) -2/3 * 3/5 + 5/2 – 3/5 * 1/6 (ii) 2/5 * (3/-7) – 1/6 * 3/2 + 1/14 * 2/5 Answer: (i) -2/3 * 3/5 + 5/2 – 3/5 * 1/6 = -2/3 * 3/5 – 3/5 * 1/6 + 5/2 [Using associative property] = 3/5 * (-2/3 – 1/6) + 5/2 [Using distributive property] = 3/5 * {(-4 - 1)/6} + 5/2 [LCM (3, 2) = 6] = 3/5 * (-5/6) + 5/2 = -3/6 + 5/2 = -1/2 + 5/2 = (-1 + 5)/2 = 4/2 = 2 (ii) 2/5 * (3/-7) – 1/6 * 3/2 + 1/14 * 2/5 = 2/5 * (-3/7) + 1/14 * 2/5 – 1/6 * 3/2 [Using associative property] = 2/5 * (-3/7 + 1/14) – 1/2 * 1/2 [Using distributive property]
= 2/5 * {(-6 + 1)/14} – 1/4 [LCM (7, 14) = 14] = 2/5 * (-5/14) – 1/4 = -1/7 – 1/4 = (-4 -7)/28 [LCM (7, 4) = 28] = -11/28 |
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