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Core Maths people? Help please!

The question is to sketch the graph of y= (x+1)(2x-1)(x-3) how would i go about doing this question? Like the steps to sketch it ?? Thanks

Reply 1

nucdev

Well it would have a cubic shape for a start. It would cross the x-axis when y=0 so when x=-1, 0.5 and 3.

Given you the starting points, I'm sure you can work out the next bit.

Reply 2

EmmaWoodley

Original post by nucdev

Well it would have a cubic shape for a start. It would cross the x-axis when y=0 so when x=-1, 0.5 and 3.

Given you the starting points, I'm sure you can work out the next bit.

Don't worry Ive got it now! Thanks for helping though

Reply 3

Zacken

Also, look at the behaviour of

y

x \to \pm \infty

Reply 4

EmmaWoodley

Original post by Zacken

Also, look at the behaviour of

y

x \to \pm \infty

for y= x(x+1)(2-x) how do we know whether its a negative of positive shape? I get how to find the intersection of x axis but how can i do the shape from that?

Reply 5

Ebony & Ivory

Original post by EmmaWoodley

for y= x(x+1)(2-x) how do we know whether its a negative of positive shape? I get how to find the intersection of x axis but how can i do the shape from that?

Can you see that if you were to expand the brackets, you'd get a negative x^3 coefficient?

That means it will go down, up, down

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