1)7^2x - 6×7^x + 5 =0 2) 2^3-2x - 3×2^1-x + 1 = 0

Question

1)7^2x - 6×7^x + 5 =0
2) 2^3-2x - 3×2^1-x + 1 = 0

Answer 1

1) 7^x=t, t>0
t²-6t+5=0
D=36-20=16
t1=(6-4)/2=1
t2=(6+4)/2=5 -(логарифмический корень)
7^x=1
x=0
2) 8*2^-2x-6*2^-x+1=0
2^-x=t, t>0
8t²-6t+1=0
D=36-32=4
t1=(6-2)/8=1/2
t2=(6+2)/8=1
2^-x=2^-1
x1=1
2^-x=1
-x=0
x2=0