document.write( "Question 203255: A certain number is added to 20, and the same number is also added to 21; the product of the two sums is 930. What is the number ? \n" ); document.write( "
Algebra.Com's Answer #153349 by ankor@dixie-net.com(22740)\"\" \"About 
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A certain number is added to 20,
\n" ); document.write( "That's (x+20)
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\n" ); document.write( " and the same number is also added to 21;
\n" ); document.write( "That's (x+21)
\n" ); document.write( ":
\n" ); document.write( " the product of the two sums is 930.
\n" ); document.write( "(x+20)*(x+21) = 390
\n" ); document.write( "FOIL
\n" ); document.write( "x^2 + 41x + 420 = 930
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\n" ); document.write( "x^2 + 41x + 420 - 930 = 0
\n" ); document.write( ":
\n" ); document.write( "x^2 + 41x - 510 = 0
\n" ); document.write( "Factor
\n" ); document.write( "(x+51)(x-10) = 0
\n" ); document.write( "Two solutions
\n" ); document.write( "x = -51
\n" ); document.write( "x = +10
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\n" ); document.write( "You can check and see that both solutions are valid\r
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