document.write( "Question 519838: please help me solve 5k^2+3k-2=0 by completing the square \n" ); document.write( "
Algebra.Com's Answer #345838 by oberobic(2304)\"\" \"About 
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5k^2 +3k -2 = 0 can be factored, so you do not need to complete the square.
\n" ); document.write( "(5k-2)(k+1) = 0
\n" ); document.write( "so
\n" ); document.write( "k = -1 or 2/5
\n" ); document.write( ".
\n" ); document.write( "Check using FOIL
\n" ); document.write( "5k^2 +5k -2k -2 = 5k^2 +3k -2 = 0
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\n" ); document.write( "Of course you can complete the square
\n" ); document.write( "5k^2 +3k -2 = 0
\n" ); document.write( "Add 2 to both sides
\n" ); document.write( "5k^2 +3k = 2
\n" ); document.write( "Divide through by coefficient of the squared term
\n" ); document.write( "k^2 + 3/5k = 2/5
\n" ); document.write( "Take 1/2 of the coefficient of the 'k' term, square it and add to the left and right sides.
\n" ); document.write( "1/2*3/5 = 3/10
\n" ); document.write( "(3/10)^2 = 9/100
\n" ); document.write( "k^2 + 3/5k + 9/100 = 2/5 + 9/100
\n" ); document.write( "(k + 3/10)^2 = 2/5 + 9/100
\n" ); document.write( "k + 3/10 = sqrt(2/5 + 9/100)
\n" ); document.write( "k + 3/10 = sqrt(40/100 + 9/100)
\n" ); document.write( "k + 3/10 = sqrt(49/100)
\n" ); document.write( "k + 3/10 = +or- 7/10
\n" ); document.write( "so
\n" ); document.write( "k = 7/10 -3/10 = 4/10 = 2/5
\n" ); document.write( "or
\n" ); document.write( "k = -7/10 -3/10 = -10/10 = -1
\n" ); document.write( ".
\n" ); document.write( "Same answer, either way.
\n" ); document.write( ".
\n" ); document.write( "Done.
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