Equation of a tangent to the graph of a function parallel to a line

[covenm1]

Could you please help me find the answer to this question. (I don't understand it.) Thanks a lot.

What is the equation of a tangent to the graph of a function [FONT=MathJax_Math-italic]y[/FONT][FONT=MathJax_Main]=[/FONT][FONT=MathJax_Math-italic]x[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Main]1/[/FONT][FONT=MathJax_Math-italic]x^[/FONT][FONT=MathJax_Main]2[/FONT] which is parallel to the line [FONT=MathJax_Math-italic]y[/FONT][FONT=MathJax_Main]=[/FONT][FONT=MathJax_Main]3[/FONT][FONT=MathJax_Math-italic]x[/FONT]?
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[HallsofIvy]

In other words, they are asking you to find a point on the graph of \(\displaystyle y= x- \frac{1}{x^2}= x- x^{-2}\) where the tangent line is parallel to y= 3x. You should know that two lines are parallel if and only if the have the same slope and that the slope of y= 3x is 3. Further you should know that the derivative of a function, at a point, is the slope of the tangent line there. So this problem is asking you to find a point on the graph \(\displaystyle y= x- x^{-2}\) where the derivative is 3. Then find the equation of that tangent line- the equation of the line through that point with slope 3.