document.write( "Question 449383: Hey, Im in much need of help to figure out how to factor/solve qudaratic equations that are not in X^2+bx+c=0 form. for example,how do you factor 4x^2=4x+5? \n" ); document.write( "
Algebra.Com's Answer #309135 by stanbon(75887)![]() ![]() ![]() You can put this solution on YOUR website! how do you factor 4x^2=4x+5? \n" ); document.write( "--- \n" ); document.write( "Rearrange: \n" ); document.write( "4x^2 - 4x - 5 = 0 \n" ); document.write( "---- \n" ); document.write( "Using the quadratic formula: \n" ); document.write( "x = [4 +- sqrt(16-4*4*-5)]/(2*4) \n" ); document.write( "--------------------- \n" ); document.write( "x = [4 +- sqrt(96)]/8 \n" ); document.write( "----- \n" ); document.write( "x = [4 +- 4sqrt(6)]/8 \n" ); document.write( "---- \n" ); document.write( "r1 = (1/2)+(1/2)sqrt(6) or r2 = (1/2)-(1/2)sqrt(6) \n" ); document.write( "----- \n" ); document.write( "Each of these is a root of the quadratic. \n" ); document.write( "--- \n" ); document.write( "The factored form would be (x-r1)(x-r2) = 0 \n" ); document.write( "=============================================== \n" ); document.write( "So the quadratic formula can ALWAYS be used to factor \n" ); document.write( "a quadratic polynomial. \n" ); document.write( "=============================================== \n" ); document.write( "If you are familiar with FOIL, Inverse FOIL can \n" ); document.write( "be used to factor some quadratics. \n" ); document.write( "---- \n" ); document.write( "Example: \n" ); document.write( " 2x^2+7x-15 = 0 \n" ); document.write( "ac = 2*-15 = -30 \n" ); document.write( "b = 7 \n" ); document.write( "---- \n" ); document.write( "Think of 2 numbers whose product is ac and whose sum is b: \n" ); document.write( "ac = 10*-3 = -30 \n" ); document.write( "b = 10+ -3 = 7 \n" ); document.write( "----- \n" ); document.write( "Rewrite the quadratic replacing the \"b-term\": \n" ); document.write( "2x^2 + 10x-3x -15 = 0 \n" ); document.write( "----- \n" ); document.write( "Factor the 1st two and the last two terms separately: \n" ); document.write( "2x(x+5)-3(x+5) = 0 \n" ); document.write( "Factor again: \n" ); document.write( "(x+5)(2x-3) = 0 \n" ); document.write( "============================= \n" ); document.write( "Cheers, \n" ); document.write( "Stan H. \n" ); document.write( "============================= \n" ); document.write( " \n" ); document.write( " |