Make tables to find the solution to 2^−x = 4^x + 3. take the integer values of x only between −3 and 3.

X    2^(-x)    4^(x+3)

-3    8          1

-2    4          4

-1    0        16

0      1        64

1      0.5      256

2      0.25    1024

3      0.125  4096

The solution is x = -2 because both functions return the same value, i.e. 4.