Polynomial Q. (1 Viewer)

[chingyloke]

Can someone help me with this one?

Find the equation of the cubic polynomial in the sketch below.

Diagram is attached..but yeh, has a turning point at x=-3, x=0 and x=5

 

[lolokay]

y = -2(x+3)(x+3)(x-5) ?

just from factorising it + adding the constant the will make y(0) = 90

 

[kurt.physics]

Can someone help me with this one?

Find the equation of the cubic polynomial in the sketch below.

Diagram is attached..but yeh, has a turning point at x=-3, x=0 and x=5

i just looked at the -3 intercept and saw it only touched it once; did not go through it, hence it is a double root ie (x+3)^2 will be part of the equation.

Secondly we can see that it intersects at x = 5, hence (x-5) is part of the equation.

Also, the graph starts from the top left corner, thus i can tell that i will be negative (the equation that is).

So we currently have

y = -(x-5)(x+3)^2

we know that this is not finnished, as the y-intercept is not 90, so the equation must be in the form

y = -a(x-5)(x+3)^2

we put in the co-ordinate (0,90) to find out that a = 2, hence the equation is