## anonymous 5 years ago what is the LCM of 15x,12x? I am tutoring a student who says that one simply drops the x? That can't be right

1. anonymous

You can't drop the x, since you don't know what its factors compose of. The lcm is instead $\frac{12x \cdot 15x}{gcd(12x, 15x)}$ which should make enough sense; you need to multiply 12x and 15x together to find a common denominator, then divide by the greatest common denominator of that product.

the LCD is the smallest number that has the factors of 12x and 15x

the factors (prime) of 12 is 2*2*3 and 15 is 5*3 so the LCD must be 2*2*3*5 or 60

4. anonymous

hello

5. anonymous

all

I forgot to include the x !! 60x