Question 942773
Don't forget to use parentheses around the exponents.
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a){{{7^(x+1) + 7^x + 7^(x-1) = 399}}}
{{{49*7^(x-1)+7*7^(x-1)+7^(x-1)=399}}}
{{{(57)7^(x-1)=399}}}
{{{7^(x-1)=7}}}
{{{x-1=1}}}
{{{x=2}}}
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b){{{4^(x+2)5^(x+1)=32000}}}
{{{16*4^x*5*5^x=32000}}}
{{{20^x=400}}}
{{{x=2}}}
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c){{{2^(x-3)5^(x+1)=625}}}
{{{(1/2^3)*2^x*5*5^x=625}}}
{{{(1/8)*2^x*5*5^x=625}}}
{{{10^x=1000}}}
{{{x=3}}}