document.write( "Question 494576: Hi, I really need help please.\r
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document.write( "In solving the equation (x + 1)(x – 2) = 54, Eric stated that the solution would be
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document.write( "x + 1 = 54 => x = 53
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document.write( "or
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document.write( "(x – 2) = 54 => x = 56
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document.write( "However, at least one of these solutions fails to work when substituted back into the original equation. Why is that? Please help Eric to understand better; solve the problem yourself, and explain your reasoning. \n" );
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Algebra.Com's Answer #335703 by htmentor(1343)![]() ![]() You can put this solution on YOUR website! In solving the equation (x + 1)(x – 2) = 54, Eric stated that the solution would be \n" ); document.write( "x + 1 = 54 => x = 53 \n" ); document.write( "or \n" ); document.write( "(x – 2) = 54 => x = 56 \n" ); document.write( "However, at least one of these solutions fails to work when substituted back into the original equation. Why is that? Please help Eric to understand better; solve the problem yourself, and explain your reasoning. \n" ); document.write( "=============================================================== \n" ); document.write( "Eric's reasoning is only valid if the RHS of the equation is equal to 0. \n" ); document.write( "Then if either of the two factors are equal to 0, this makes the whole \n" ); document.write( "expression equal to 0. If the RHS is not equal to 0, then the two factors when \n" ); document.write( "multiplied together have to equal the RHS, not each of the factors individually. \n" ); document.write( "To solve, first multiply the two factors and then subtract the RHS: \n" ); document.write( "(x+1)(x-2) = 54 \n" ); document.write( "x^2 - x - 2 = 54 \n" ); document.write( "x^2 - x - 56 = 0 \n" ); document.write( "The above equation can be factored as: \n" ); document.write( "(x-8)(x+7) = 0 \n" ); document.write( "We see from this that the solutions are x = 8 and x = -7 \n" ); document.write( " |