7^(x+2)-14·7^x=5,
7²·7^x-14·7^x=5,
49·7^x-14·7^x=5,
35·7^x=5,
7·7^x=1,
7^x=1/7,
7^x=(7)⁻¹,
x=-1.
10·5^(x-1)+5^(x+1)=7,
10·(5^x)/5+(5^x)·5=7,
2·5^x+5·5^x=7,
7·5^x=7,
5^x=1,
5^x=(5)⁰,
x=0.
2^x+2^(x+1)+2^(x+2)+2^(x+3)=30,
2^x+2·2^x+2²·2^x+2³·2^x·=30,
2^x(1+2+4+8)=30,
15·2^x=30,
2^x=2,
2^x=2¹,
x=1.
2^x+2^(x+1)+2^(x+2)=5^x+5^(x+1),
2^x+2·2^x+2²·2^x=5^x+5·5^x,
2^x(1+2+4)=5^x(1+5),
6·2^x=6·5^x,
2^x=5^x,
2^x/5^x=1,
(2/5)^x=(2/5)⁰,
x=0.
4^(x-1)+4^x+4^(x+1)=84,
4⁻¹·4^x+4^x+4¹·4^x=84,
4^x(1/4+1+4)=84,
4^x(1+4+16)/4=84,
(21/4)·4^x=84,
4^x=84·4/21,
4^x=16,
4^x=4²,
x=2.
3^(x+2)-3^(x+1)+3^x=21,
3²·3^x-3·3^x+3^x=21,
3^x(9-3+1)=21,
7·3^x=21
3^x=3,
3^x=3¹,
x=1.
5·2^√x-3·2^(√x-1)=56,
5·2^√x-3·2⁻¹·2^x=56,
2^√x(5-3/2)=56,
2^√x(5-1,5)=56,
3,5·2^√x=56,
2^√x=16,
2^√x=2⁴,
√x=4,
(√x)²=4²,
x=16.