document.write( "Question 983422: Given that a - b = 10 and 2 (a^2 - b^2) = 640 .find the value of a + b\r
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Algebra.Com's Answer #604219 by Cromlix(4381)![]() ![]() You can put this solution on YOUR website! Hi there, \n" ); document.write( "a - b = 10 \n" ); document.write( "so a = b + 10 \n" ); document.write( "2(a^2 - b^2) = 640 \n" ); document.write( "Multiply out \n" ); document.write( "2a^2 - 2b^2 = 640 \n" ); document.write( "Substitute for 'a' (b + 10) \n" ); document.write( "2(b + 10)^2 - 2b^2 = 640 \n" ); document.write( "Expand \n" ); document.write( "2(b^2 + 20b + 100) - 2b^2 = 640 \n" ); document.write( "2b^2 + 40b + 200 - 2b^2 = 640 \n" ); document.write( "Collect like terms \n" ); document.write( "2b^2 - 2b^2 + 40b = 640 - 200 \n" ); document.write( "40b = 440 \n" ); document.write( "b = 11 \n" ); document.write( "Substitute b = 11 into \n" ); document.write( "a - b = 10 \n" ); document.write( "a - 11 = 10 \n" ); document.write( "a = 10 + 11 \n" ); document.write( "a = 21 \n" ); document.write( "Therefore: \n" ); document.write( "a + b = 21 + 11 = 32 \n" ); document.write( "Hope this helps:-) \n" ); document.write( " \n" ); document.write( " |