Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

C4 remainder theorem question

The question i'm struggling with is 'Find the value of k if the remainder when x^3+4x^2+kx+3 is divided by 3x-2 is 5.' Could anyone tell me the answer (and possibly their workings)? Thanks

Using the remainder theorem, f(2/3)=5 where f(x)=x^3+4x^2+kx+3. Use this information to solve for k.

Original post by rachelbutler

The question i'm struggling with is 'Find the value of k if the remainder when x^3+4x^2+kx+3 is divided by 3x-2 is 5.' Could anyone tell me the answer (and possibly their workings)? Thanks

Do you know how the remainder theorem works?

OP

Oh okay, so do you just substitute 2/3 in and put it =5 and rearrange to find k?

Original post by rachelbutler

Oh okay, so do you just substitute 2/3 in and put it =5 and rearrange to find k?

Do you understand why you need to do this

OP

sort of.. you know there's a remainder of 5 so when you divide by 3x-2 it has to =5.

Original post by rachelbutler

sort of.. you know there's a remainder of 5 so when you divide by 3x-2 it has to =5.

Hmmmm

Do you know why you are using 2/3

OP

not entirely, something to do with 3x-2=0 and finding that x=2/3

Original post by rachelbutler

not entirely, something to do with 3x-2=0 and finding that x=2/3

Yes, that is why

OP

okay, thank you for your help! It is appreciated :smile:

:smile:

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