Can somebody help me with 3ab^2 - 3abc factorizing it

Question

saifoo.khan · Answer

3ab(b-c)

anonymous · Answer

ok good you know what you are doing haha i need help on a few if you would?

saifoo.khan · Answer

umm, u are doing a test or somthing? lol.
i can try for sure.

anonymous · Answer

no end of term homework b^4 - ab^3 + b^2c

saifoo.khan · Answer

$$b^2 (-a b+b^2+c) $$

anonymous · Answer

could you explain how you do it?

anonymous · Answer

ok sorry that was an easier one now can you help where it is complicated? 3yz - 6z - 9 and would it be 3( y^2- 2z - 3)?

saifoo.khan · Answer

correct.

anonymous · Answer

y^3z^2 - y^2Z^2 - y^2Z^2 1= y^2z(yz - z -z^2)?

lilg132 · Answer

you have to look at which of the variables appears in all of them

so for example

in the last one saifoo answered

b appeared the most

but as you can see all of them have atleast more then b^2 which means

we can write b^2 outside the bracket

and we need to put inside that bracket something * b^2 which will give us 

b^4 - ab^3 + b^2c

so you would put

b^2(b^2 - ab + c)

when you expand it you get

b^2 * b^2 = b^4
b^2 * -ab = -ab^3
b^2 * + c = b^2c

that is how you check if it is correct

but the main thing you have to look out for is what appears in all of them e.g. what variable or what number can be used to multiply with another variable or number to give you that equation

anonymous · Answer

Ok thank you so much... was that last one I did correct?

lilg132 · Answer

yes it is correct