Medals for help:

a) Show that the substitution y = 2^x transforms the equation 2^2x - 7(2^x) = 8 into the equation y^2 - 7y - 8 - 0.

b) Hence, solve the original equation for x.

I managed to sort out part A fine but I'm not sure what to do in part B.

Question

Medals for help:

a) Show that the substitution y = 2^x transforms the equation 2^2x - 7(2^x) = 8 into the equation y^2 - 7y - 8 - 0.

b) Hence, solve the original equation for x.

I managed to sort out part A fine but I'm not sure what to do in part B.

anonymous · Answer

$$y = 2^{x}$$$$2^{2x} - 7(2{^x}) = 8$$$$y^{2} - 7y - 8 = 0$$
Those forms may be more understandable.