document.write( "Question 925026: The sum of five times a number and five times its square is 210. Determine the numbers \n" ); document.write( "
Algebra.Com's Answer #561273 by DrBeeee(684)![]() ![]() ![]() You can put this solution on YOUR website! Let n be the number we want. \n" ); document.write( "Then we have \n" ); document.write( "(1) 5n + 5n^2 = 210 or after dividing both sides by 5 we have \n" ); document.write( "(2) n + n^2 = 42 or \n" ); document.write( "(3) n^2 + n - 42 = 0 \n" ); document.write( "Now factor (3) and get \n" ); document.write( "(4) (n+7)*(n-6) = 0, giving us the roots \n" ); document.write( "(5) n = -7,6 \n" ); document.write( "Let's check the answers with (1). \n" ); document.write( "Is (5*(-7) + 5*(-7)^2 = 210)? \n" ); document.write( "Is (-35 + 5*49 = 210)? \n" ); document.write( "Is (-35 + 245 = 210)? \n" ); document.write( "Is (210 = 210)? Yes \n" ); document.write( "Is (5*(6) + 5*(6)^2 = 210)? \n" ); document.write( "Is (30 + 5*36 = 210)? \n" ); document.write( "Is (30 + 180 = 210)? \n" ); document.write( "Is (210 = 210)? Yes \n" ); document.write( "Answer: The set {-7,6} satisfies the problem statement. \n" ); document.write( " |