Question

lcm x^2+9x, x^2-9x

Answer 1

first factorise each expression

Answer 2

ok

Answer 3

what do you get?

Answer 4

x(x+9) x^2+9x

Answer 5

you have factorised the first expression correctly, now also factorise the second expression please

Answer 6

x(x-9)

Answer 7

ok, so now you need to find the lcm of x(x+9) and x(x-9)

Answer 8

you should notice that both expressions have x as a common factor

Answer 9

yes

Answer 10

one way to work out the lcm is as follows:

lcm(a,b) = (a*b)/gcd(a,b)

where gcd is the greatest common divisor, which in this case is 'x'

Answer 11

so my lcm is x?

Answer 12

no

Answer 13

the gcd in this case is 'x'

Answer 14

i know but im trying to find the lcm

Answer 15

lcm(a,b) = (a*b)/gcd(a,b)

Answer 16

you know a, b and the gcd

Answer 17

Very simple. Take the largest power of every DIFFERENT factor

Answer 18

You have three different factors and each is to the first power so take the first power of every different factor and there's your LCM

Answer 19

so it would be 2?

Answer 20

no

Answer 21

cuz its a power of 2

Answer 22

lcm( x(x+9), x(x-9) ) = x(x+9) * x(x-9) / x

Answer 23

o i c

Answer 24

LCM = x(x-9)(x+9)

Answer 25

thank u

Answer 26

yw

Answer 27

Largest Power of Every Different Factor
Different factors are x, x+9, x-9
Each is to the first power
So largest power of every different factor is x(x-9)(x+9)
Works every time.

Answer 28

as does:

lcm(a,b) = (a*b)/gcd(a,b)

Answer 29

Absolutely however more complicated.

Answer 30

really?

Answer 31

Maybe it's whatever one is used to. We'll let the asker decide which he/she wishes to use.

Answer 32

Choice is good.

Answer 33

agreed :)

Answer 34

thanks guys :)

Answer 35

yw

Answer 36

yw