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8-54.

What is the stretch factor for the equation of the graph in part (c) of problem 8-45? Write the exact equation of the function.

Using the factors, you can work backwards to find the beginning of the equation. The double root at $x = -2$ gives you $(x + 2)^2$, the root at $x = 1$ gives you ($x - 1$). Substitute the point ($0, 8$) into the equation$y = a(x + 2)^2(x - 1)$ and solve for $a$.

The stretch factor is $-2$. The equation is $f(x) = -2(x + 2)^2(x - 1)$.