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I don't understand algebra/indices, please help!

Hello, I don't understand the laws or what I am supposed to do in order to simplify this equation...

4x3 + 16x2 - 8x

Online calculators give me the answer: 4x (x2 + 4x - 2)

I've no idea if this is correct, but whether it is or isn't I'd like to know how you go about simplifying this.

Thanks for any help, Dan.
Honestly just go on www.examsolutions.net and browse your heart out
Original post by mr_tash
Hello, I don't understand the laws or what I am supposed to do in order to simplify this equation...

4x3 + 16x2 - 8x

Online calculators give me the answer: 4x (x2 + 4x - 2)

I've no idea if this is correct, but whether it is or isn't I'd like to know how you go about simplifying this.

Thanks for any help, Dan.


look for common factors: 4x is in every term so you can take it outside the bracket.
Reply 3
Avatar for davros
davros
16
Original post by mr_tash
Hello, I don't understand the laws or what I am supposed to do in order to simplify this equation...

4x3 + 16x2 - 8x

Online calculators give me the answer: 4x (x2 + 4x - 2)

I've no idea if this is correct, but whether it is or isn't I'd like to know how you go about simplifying this.

Thanks for any help, Dan.


Just a point on terminology - this is an expression, not an equation (there's no equals sign) :smile:

"Simplify" in this case means "factorize".

Hopefully in this case you can see that 'x' is a common factor of every term in the expression so you can take that outside a bracket. If you now look at the numbers, you can see that 4 also divides every term so you can take that outside the bracket too. Therefore you have 4x outside the bracket and another new expression inside the bracket. When you are more confident with these things you can take the 4x outside all in one go :smile:
Original post by mr_tash
Hello, I don't understand the laws or what I am supposed to do in order to simplify this equation...

4x3 + 16x2 - 8x

Online calculators give me the answer: 4x (x2 + 4x - 2)

I've no idea if this is correct, but whether it is or isn't I'd like to know how you go about simplifying this.

Thanks for any help, Dan.

Can you expand 4x(x2+4x−2)4x(x^2+4x-2), just to verify to yourself that it is indeed the same as 4x3+16x2−8x4x^3 + 16x^2 - 8x? You might find that helps you to see what's going on.
Reply 5
Avatar for mr_tash
mr_tash
OP
Thanks so much guys. Sorry for the delay in replyng, I've just gotten round to attempting my assignment again! All the responses have been great. I actually understand what I'm doing now. I see how 4x can be multiplied by x2, 4x and -2 to factorise the expression. The next problem I have is I'm asked me to outline the laws of indices I've used to 'simplify'. Would I be wrong in saying that I haven't used any laws of indices? I feel like I just used the highest common factor, and algebra.

Thanks again.
Try to use this link:

It will help you differentiate between when to use the laws of indices and when to not. In factorisation, you don't use the laws of indices, as you are finding common factors. When solving or simplifying, you might need to.


Unparseable latex formula:

x^2 * x^8 = x^2^+^8 = x^1^0


x2+2x2=x2(1+2)x^2 + 2x^2 = x^2(1 + 2)
(edited 9 years ago)
Original post by mr_tash
Thanks so much guys. Sorry for the delay in replyng, I've just gotten round to attempting my assignment again! All the responses have been great. I actually understand what I'm doing now. I see how 4x can be multiplied by x2, 4x and -2 to factorise the expression. The next problem I have is I'm asked me to outline the laws of indices I've used to 'simplify'. Would I be wrong in saying that I haven't used any laws of indices? I feel like I just used the highest common factor, and algebra.

Thanks again.


You used the laws of indices that we use when multiplying or dividing

But you used them intuitively because the numbers were small

Knowing that x^3 = x^2 times x is using the law that says 3=2+1
Reply 8
Avatar for mr_tash
mr_tash
OP
Dig. That's the kind of thing I wrote down. Thanks people. I'm training to be an electrician. These indices sure will get me through my day to day tasks on site!

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