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How to find the LCM of two or more numbers (or expressions)

How to find the LCM of two or more numbers (or expressions). 1) For of each number (or expression) get the prime decomposition. Ex: Find the LCM for 40, 30, 36 40 = 2 3 • 8 30 = 2 • 3•5 36 = 2 2 • 3 2.

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How to find the LCM of two or more numbers (or expressions)

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  1. How to find the LCM of two or more numbers (or expressions) 1) For of each number (or expression) get the prime decomposition Ex: Find the LCM for 40, 30, 36 40 = 23• 8 30 = 2 • 3•5 36 = 22 •32 2) For each factor in the decompositions select the one with maximum exponent For 2 we select 23 For 3 we select 32 For 5 we select 51 LCM = 23 •32 •5 3) The product of all these selections is the LCM LCM = 360

  2. Find the LCM for 6x-6, 4x2-4, x2+2x-3 • First get the prime factorization for each polynomial • 6x - 6 = 6(x -1) =2·3 (x -1) • 4x2 - 4 = 4(x2 -1) = 22(x +1)(x -1) • x2 + 2x - 3 = 3 (x – 1)(x +1) ( x +3) • For 2 select 22 • For 3 select 3 • For x -1 select x -1 • For x +1 select x +1 • For x +3 select x +3 • So LCM = 22· 3 (x –1)(x +1)( x +3) • LCM = 12 (x – 1)(x +1)( x +3)

  3. Find the value of We need to find the LCD (LCM for the denominator ) Since 9 = 32 8 = 23 24 = 23·3 So the LCD = 23· 32 = 8·9 = 72 Rewriting the fraction with denominator 72 …

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