1. (2/7)^х=7/2 2. 2^2х - 3*2^х-4=0

Question

1. (2/7)^х=7/2
2. 2^2х - 3*2^х-4=0

Answer 1

Вот, держи. Вроде, все просто

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Answer 2

1. (2/7)^x=7/2. (2/7)^x=(2/7)^(-1). x=-1.
2. 2^(2x)-3•2^x-4=0.
2^x=t. 2^(2x)=t².
t²-3t-4=0.
t²+t-4t-4=0.
t(t+1)-4(t+1)=0.
(t+1)(t-4)=0.
2^x=-1. ☞ ∅
2^x=2². x=2.