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Factorising

Hi, I'm self-teaching GCSE maths. I can do C grade factorising easily, however, I'm struggling to understand how to do some B grade questions, and the book I'm using doesn't explain it as much as I'd like. The questions I'm struggling with are questions such as these where there are brackets already involved:

1. p(p + 4) -3p
2. (2t + s)(2t - s) + (2t - s)
3. (2d+1)^2 + (2d + 1)

The answers are:

1. p(p +1)
2. (2t - s) (2t + s +1)
3. 2(2d +1) (d + 1)

Would someone be able to do a step-by-step with how to get to these answers? I understand where the common factor has came from in no. 2 and 3., but don't know where the rest of the answer came from. I have no clue about question 1. Better yet, if anyone knows somewhere that explains these sorts of questions, that would be great. I could only find tutorials for the easier questions.
Reply 1
Avatar for davros
davros
16
Original post by _N_
Hi, I'm self-teaching GCSE maths. I can do C grade factorising easily, however, I'm struggling to understand how to do some B grade questions, and the book I'm using doesn't explain it as much as I'd like. The questions I'm struggling with are questions such as these where there are brackets already involved:

1. p(p + 4) -3p
2. (2t + s)(2t - s) + (2t - s)
3. (2d+1)^2 + (2d + 1)

The answers are:

1. p(p +1)
2. (2t - s) (2t + s +1)
3. 2(2d +1) (d + 1)

Would someone be able to do a step-by-step with how to get to these answers? I understand where the common factor has came from in no. 2 and 3., but don't know where the rest of the answer came from. I have no clue about question 1. Better yet, if anyone knows somewhere that explains these sorts of questions, that would be great. I could only find tutorials for the easier questions.


For Q1, can you see that p is a factor of p(p+4) and 3p? So in that case you should be looking to take out a factor p to start with...
Reply 2
Avatar for 2710
2710
18
Original post by _N_
Hi, I'm self-teaching GCSE maths. I can do C grade factorising easily, however, I'm struggling to understand how to do some B grade questions, and the book I'm using doesn't explain it as much as I'd like. The questions I'm struggling with are questions such as these where there are brackets already involved:

1. p(p + 4) -3p
2. (2t + s)(2t - s) + (2t - s)
3. (2d+1)^2 + (2d + 1)

The answers are:

1. p(p +1)
2. (2t - s) (2t + s +1)
3. 2(2d +1) (d + 1)


For question 1, you should do as above said, if you cant see it then you can break it out you get p^2 +4p-3p which you gives you your required answer.

2) Look at the two terms. Term 1 is everything before the + sign and term 2 is everything after. You can immediately see that 2t-s is the common factor.

3) same as above.

Posted from TSR Mobile
(edited 10 years ago)

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