Question

Решите уравнение 4* 0.5^{x+1} - 0.5^{x} + 0.5^{x-2} =20

Answer 1

4*0.5^x*0.5-0.5^x+0.5^x/0.5^2=20      0.5^x(2-1+4)=20     0.5^x*5=20       0.5^x=4           (1/2)^x=(1/2)^-2      x=-2