PHP Solve Parabolic Equation

How can I write a code in PHP that will solve for x in this equation

1.2(x^3) - 15(x^2) + 100x - 140 = y

In this case, y is the input and x is the output with the restriction of X: [1,100]

 

Brute-force search?

 

No, it is for calculating level based on experience point. I am developing a gaming site.

 

Y is the experience point, and X is the level

 

What is the range of a Y?

 

Y [0, 1059860]

 

This equation has no solutions

 

Example code for simple equation:

<?
set_time_limit(1000);
#y
$y=0;
#x min
$x=-100;
$x_max=100;
$array=array(); $equ=array();
#timestart
$time=time();
while(true){
#Equation
$ex=$x*$x-$x-2;
if($ex==$y){
$equ[]=$x;
}
if($x==$x_max){break;}
$x+=1;
}
print_r($equ);
?>

Code (markup):

Example code for your equation:

<?
set_time_limit(1000);
#y
$y=0;
#x min
$x=1;
$x_max=100;
$array=array(); $equ=array();
#timestart
$time=time();
while(true){
#Equation
$ex=1.2*($x*$x*$x)-15*($x*$x)+100*$x-140;
if($ex==$y){
$equ[]=$x;
}
if($x==$x_max){break;}
$x+=1;
}
print_r($equ);
?>

Code (markup):

 

Post the equation in the form

x = .....

and someone (me, if no one else) will give you the code for it. (We have to leave SOME work for you to do.)

 

Thank you! One question, how can i add the input y into the code.