How to find the LCM of two or more numbers (or expressions) Ex: Find the LCM for 40, 30, = = = For 2 we select 2323 For 3 we select 3232 For 5 we select 5151 LCM = ) For of each number (or expression) get the prime decomposition 2) For each factor in the decompositions select the one with maximum exponent 3) The product of all Answer: LCM = 360
Find the LCM for 6x-6, 4x 2 -4, x 2 +2x-3 First get the prime factorization for each polynomial 6x - 6 = 6(x -1) = 2·3 (x -1) 4x = 4(x 2 -1) = 2 (x +1) (x -1) x 2 + 2x - 3 = 3 (x – 1) (x +1) ( x +3) For 2 we select 2 For 3 we select 3 For x we select x For x +1 we select x +1 For x +3 we select x +3 LCM = 2 2 (3)(x – 1) (x +1) ( x +3) Answer: LCM = 12 (x –1)(x +1)( x +3)
We need to find the LCD (LCM for the denominator ) Since 9 = = = ·3 So the LCD = · = 8·9 = 72 Rewriting the fraction with denominator 72 … Find the value of Adding Fractions