Question

Resolva as equações em R.
A)$2^{2X}$-10.$2^{X}$+16=0
B)$9^{X}$-7.$3^{X}$-18=0
C)$3^{X-4}$=81

Answer 1

A)

${2}^{x} = y$

${y}^{2} - 10y + 16 = 0 \\ y1 = 8 \\ y2 = 2$

${2}^{x} = 8 \\ x = 3 \\ \\ {2}^{x} = 2 \\ x = 1 \\ s = {8 \: e \: 1}$

B)

${3}^{x} = y$

${y}^{2} - 7y - 18 = 0 \\ y1 = 9 \\ y2 = - 2 \\ {3}^{x} = 9 \\ x = 2$

ignorei o valor negativo

S=(2)

C)

${3}^{x} \times {3}^{ - 4} = {3}^{4} \\ {3}^{x} ={3}^{8} \\ x = 8$