Maths help

The question is asking me to circle the equation with roots 4 and -8 and the options are: 4x(x-8)=0, (x-4)(x+8)=0, x^2 -32 = 0 and (x+4)(x-8)=0. The answer is not what I'm interested in but more so how to go about answering similar questions like these

Reply 1

Ano123

15

A polynomial with roots

\alpha, \beta, \gamma .... \zeta

has equation

(x-\alpha)(x-\beta)(x-\gamma)...(x-\zeta)

.
Since when you plug in one of the roots for x it will be equal to 0.

Reply 2

Katiee224

11

Ok so first of all solve each of the x values when the equation is equal to 0

For example on the first one, 4x=0 and x-8=0

what are the roots of this first equations? (ie what are the values of x)

repeat this method for the other three equations :smile:

Reply 3

theBranicAc

3

Original post by Botcampers

The question is asking me to circle the equation with roots 4 and -8 and the options are: 4x(x-8)=0, (x-4)(x+8)=0, x^2 -32 = 0 and (x+4)(x-8)=0. The answer is not what I'm interested in but more so how to go about answering similar questions like these

isn't this a question in the new gcse maths paper(aqa)

Reply 4

Botcampers

OP

7

Original post by theBranicAc

isn't this a question in the new gcse maths paper(aqa)

Not sure. My teacher gave it to me so I could revise

Reply 5

Botcampers

OP

7

Original post by Katiee224

Ok so first of all solve each of the x values when the equation is equal to 0

For example on the first one, 4x=0 and x-8=0

what are the roots of this first equations? (ie what are the values of x)

repeat this method for the other three equations :smile:

Oh! That makes sense. I was baffled by the word root but now it makes sense. Just look for the values of X. Thank you

Reply 6

Katiee224

11

Original post by Botcampers

Oh! That makes sense. I was baffled by the word root but now it makes sense. Just look for the values of X. Thank you

The values of x are when y=0. If you plotted the graph of each of these equations you would see this is where the graph crosses the x-axis.

I recommend you draw out the graphs to see visually where the routes are once you've found them. :smile:

Reply 7

Ano123

15