You are Here: Home >< Maths

# question core 3 watch

1. Given that y=(3x-7)^5 +5(3x-7)^4, show that dy/dx=45(3x-7)^3(x-1)

When i differentiated the original equation, i got:
dy/dx=15(3x-7)^4 + 60(3x-7)^3
I assume i have to simply this but i'm unsure how. So far, i have tried making dy/dx=0 and taking away 60(3x-7)^3, but this doesn't seem to work?
2. (Original post by Chelsea12345)
Given that y=(3x-7)^5 +5(3x-7)^4, show that dy/dx=45(3x-7)^3(x-1)

When i differentiated the original equation, i got:
dy/dx=15(3x-7)^4 + 60(3x-7)^3
I assume i have to simply this but i'm unsure how. So far, i have tried making dy/dx=0 and taking away 60(3x-7)^3, but this doesn't seem to work?
Although it is good that you have tried something (seriously, not in a patronising way) setting the equation to 0 isn't justified by any info given in the question.

Notice that a + b has turned into one term - which would be your hint that the question wants you to f _ _ _ _ _ _ _ e and then simplify it.
3. (Original post by Kevin De Bruyne)
Although it is good that you have tried something (seriously, not in a patronising way) setting the equation to 0 isn't justified by any info given in the question.

Notice that a + b has turned into one term - which would be your hint that the question wants you to f _ _ _ _ _ _ _ e and then simplify it.
is there meant to be a space there? or is the word not appearing?
4. (Original post by Chelsea12345)
is there meant to be a space there? or is the word not appearing?
he is trying not to give you too much help:

F _ _ _ O _ _ _ E
5. (Original post by the bear)
he is trying not to give you too much help:

F _ _ _ O _ _ _ E
Is there a C in there?
6. (Original post by RDKGames)
Is there a C in there?
F _ C _ O _ _ _ E

next !!
7. U?
8. (Original post by Chelsea12345)
Given that y=(3x-7)^5 +5(3x-7)^4, show that dy/dx=45(3x-7)^3(x-1)

When i differentiated the original equation, i got:
dy/dx=15(3x-7)^4 + 60(3x-7)^3
I assume i have to simply this but i'm unsure how. So far, i have tried making dy/dx=0 and taking away 60(3x-7)^3, but this doesn't seem to work?
What if I tell you that if we let then our expression for is simply , which can be simplified by....?

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 20, 2017
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University
Wed, 1 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams