document.write( "Question 4359: 5x^3-36x^2+189=0
\n" ); document.write( "solve for x
\n" ); document.write( "please show work \n" ); document.write( "
Algebra.Com's Answer #1978 by khwang(438)\"\" \"About 
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Step I) Try to factor out (x-3)
\n" ); document.write( " 5x^3-36x^2+189=0
\n" ); document.write( " i) Separate -36x^2 into two terms:
\n" ); document.write( " 5x^3- 15x^2 - 21x^2 + 189=0 ,
\n" ); document.write( " ii)Regrouping :
\n" ); document.write( " 5x^2(x -3) - 21(x^2 - 9) = 0
\n" ); document.write( " iii) Note (x^2 -9) = (x-3)(x+3) [a formula you should know.]
\n" ); document.write( " 5x^2(x -3) - 21(x-3)(x+3) = 0
\n" ); document.write( " iv) Factor out (x-3):
\n" ); document.write( " (x-3)[5x^2 -21(x+3)] = 0,
\n" ); document.write( " Or (x-3)[5x^2 -21 x -63] = 0.\r
\n" ); document.write( "\n" ); document.write( " Step II:
\n" ); document.write( " x - 3 = 0 implies x = 3
\n" ); document.write( " By quadratic formula on 5x^2 -21 x -63 = 0
\n" ); document.write( " we have x = [21 + sqrt(21^2 + 20 * 63)]/10
\n" ); document.write( " = [21 + 9 sqrt(21)]/ 10 (or 3/10[ 7 + 3 sqrt(21)])
\n" ); document.write( "or x = [21 - 9 sqrt(21)]/ 10
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\n" ); document.write( " Kenny\r
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