A1:5
A2:5
A3(x):5
A4:4
B1: =A1*A3^2+A2*A3-A4

ToolsGoal Seek
Set Cell: B1
To Value: 0
By Changing cell: A3

If you need more precision: ToolsOptionsCalculation, change the Iteration
options

Niek Otten

"excel nub" <excel wrote in message
...
eg. "A1*x^2 + A2*x= 4 " in cell B1
we know the values in cells A1 and A2 and both are constants.

how do we solve for x using goal seek?