document.write( "Question 936159: Use the substitution y=3^x to find the values of x which satisfy the equation
\n" ); document.write( "3^(2x+2)-10*3^(x) +1=0\r
\n" ); document.write( "\n" ); document.write( "I tried: 3^(2)*3^(x) + 3^(2) -10*3^(x) + 1 =0
\n" ); document.write( "Substituted in y: 9y + 9 - 10y + 1 = 0
\n" ); document.write( "which became: -y=-9 then y=9
\n" ); document.write( "so 3^x = 9 therefore x is 2 or so I thought.
\n" ); document.write( "The textbook answer given is -2 and 0. \r
\n" ); document.write( "\n" ); document.write( "Please could you help me and explain where I went wrong? Thank you. \n" ); document.write( "
Algebra.Com's Answer #569614 by Alan3354(69443)\"\" \"About 
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Use the substitution y=3^x to find the values of x which satisfy the equation
\n" ); document.write( "3^(2x+2)-10*3^(x) +1=0\r
\n" ); document.write( "\n" ); document.write( "I tried: 3^(2)*3^(x) + 3^(2) -10*3^(x) + 1 =0
\n" ); document.write( "It's 3^2*3^(2x) -10*3^x + 1 = 0
\n" ); document.write( "--> 9y^2 - 10y + 1 = 0
\n" ); document.write( "======================================
\n" ); document.write( "You had the right idea, but having 2 answers should make you expect a quadratic.
\n" ); document.write( "--------------------------------------
\n" ); document.write( "Substituted in y: 9y + 9 - 10y + 1 = 0
\n" ); document.write( "which became: -y=-9 then y=9
\n" ); document.write( "so 3^x = 9 therefore x is 2 or so I thought.
\n" ); document.write( "The textbook answer given is -2 and 0.
\n" ); document.write( " \n" ); document.write( "
\n" );