Question

me ajudemm, por favor!!
;_;​

Answer 1

Vamos là.

A)

5^(2x) + 20*5^x = 125

y = 5^x

y² + 20y =  125

y² + 20y + 100 = 125 + 100

(y + 10)² = 225

y + 10 = 15

y = 5

5^x = 5

x = 1 (A)

B)

2^(2x + 3) - 65*2^x = -8

8*2^(2x) - 65*2^x = -8

y = 2^x

8y²  - 65y + 8 = 0

delta

d = 65² - 4*8*8 = 3969

y1 = (65 + 63)/16 = 128/16 = 8

y2 = (65 - 63)/16 = 2/16 = 1/8

2^x1 = 8, x1 = 3

2^x2 = 1/8, x2 = -3 (D)