Answer:
x = -4.50
Explanation:
You want the solution to f(x)=g(x) for the functions f(x) = 0.4^x -4 and g(x) = 58.
Graph
The attachment shows a graph of the two functions. The solution to f(x) = g(x) is the x=coordinate of the point of intersection between the two curves:
x ≈ -4.50.
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Additional comment
Analytically, the solution is ...
0.4^x = 62 . . . . . . . add 4 to the equation f(x) = g(x)
x = log(62)/log(0.4) . . . . . take logarithms; divide by the coefficient of x
x ≈ -4.50417563059
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