Let p(x) = 2x^3 - 113 and let q be the inverse of p. Find q(137).

Thanks for whoever is going to answer this!!!

MIRB16
Jul 22, 2017

#1**+2 **

Let p(x) = 2x^3 - 113 and let q be the inverse of p. Find q(137)

Note that the inverse just reverses the original coordinates

So the coordinates of the inverse are ( 137, x)

So....putting 137 into the inverse sends us back to the otiginal "x"

So....the original coordinates were ( x, 137 )

And x will equal q (137)

So...all we need to do is to set p = 137 and solve to find this otiginal x

2x^3 - 113 = 137 add 113 to both sides

2x^3 = 250 divide both sides by 2

x^3 = 125 take the cube root of both sides

x = 5 and this is q(137)

Proof...I won't derive it but the inverse q is ∛ [ ( x + 113) / 2 ]

And q (137) = 5

CPhill
Jul 22, 2017