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**requal** consider the equations of the cubic function and the straight line.

$\displaystyle y=x^3-x$, $\displaystyle y=ax+a$

The straight line crosses the cubic function at point A(-1,0). Suppose that the straight line crosses the cubic function at two further points P($\displaystyle x_1,y_1$) and Q$\displaystyle (x_2,y_2$), where $\displaystyle x_1<x_2$.

1. Show that $\displaystyle x_1+x_2=1$

2. Hence find the equation of the line throught the point A tangent to the cubic function at a point distinct from the point A