You are Here: Home >< Maths

# a little unsure watch

1. guys sorry it's me again i was factorising
3x2 + 10x + 7 = 0

in this case, would it be appropriate to use the quadratic formula, or would it not work because 3x2 isn't exactly the same as ax
2. (Original post by entertainmyfaith)
guys sorry it's me again i was factorising
3x2 + 10x + 7 = 0

in this case, would it be appropriate to use the quadratic formula, or would it not work because 3x2 isn't exactly the same as ax
How can a quadratic formula "not work"?

Completing the square, factorising, and using the quadratic formula (which is a general result from completing the square) are all valid methods of solving a quadratic, so they all work.

You can use the quadratic formula if you want, but you can also easily factorise this quadratic too.
3. no you can use it you would just make a= three
4. (Original post by RDKGames)
How can a quadratic formula "not work"?

Completing the square, factorising, and using the quadratic formula (which is a general result from completing the square) are all valid methods of solving a quadratic, so they all work.

You can use the quadratic formula if you want, but you can also easily factorise this quadratic too.
i didn't mean the formula not working, more if it was appropriate for the method because i was just unsure if 3x2 + 10x +7 = 0 was equivalent to ax + bx + c = 0- does the squared notation affect it?
5. (Original post by entertainmyfaith)
i didn't mean the formula not working, more if it was appropriate for the method because i was just unsure if 3x2 + 10x +7 = 0 was equivalent to ax + bx + c = 0- does the squared notation affect it?
Your "ax+bx+c=0" is not a quadratic expression, so no they are no equivalent.

If you meant then yes of course they are equivalent since we just have
7. (Original post by Ex-pert)
Don't see how that's a crime. The formula would give her solutions to the equation so all that is needed to be done is plug them in the form which would give the factorised form.
8. (Original post by entertainmyfaith)
guys sorry it's me again i was factorising
3x2 + 10x + 7 = 0

in this case, would it be appropriate to use the quadratic formula, or would it not work because 3x2 isn't exactly the same as ax

[solution removed]
9. (Original post by RDKGames)
Don't see how that's a crime. The formula would give her solutions to the equation so all that is needed to be done is plug them in the form which would give the factorised form.
But there is another easier way
I dont see the reason why he is making it look so complicated
10. (Original post by Ex-pert)
But there is another easier way
I dont see the reason why he is making it look so complicated
I agree, but if that's the way she wants to try first then she can go ahead and settle on it for the time being.
11. i tried factorising it but i couldn't do it so i just used the quadratic formula. it got me the right answer
12. (Original post by entertainmyfaith)
i tried factorising it but i couldn't do it so i just used the quadratic formula. it got me the right answer
ok
13. (Original post by entertainmyfaith)
i tried factorising it but i couldn't do it so i just used the quadratic formula. it got me the right answer
Thats what i want to see
14. (Original post by entertainmyfaith)
i tried factorising it but i couldn't do it so i just used the quadratic formula. it got me the right answer
To factorise something of the form you want to look for two numbers with the following properties: and

Then you take the form and plug those in there for factorisation.

In your example, you have with and . Shouldn't take too long to notice that and are valid conditions which make those properties true.

So then you have which can be simplified further.

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: October 29, 2017
Today on TSR

### Cambridge interviews

Find out who is getting invitations

### University open days

• University of Roehampton
Sat, 17 Nov '18
• Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 17 Nov '18
• Bournemouth University
Sat, 17 Nov '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