document.write( "Question 870577: consider the polynomial P(x)=x^3+3x^2+(3-k)x+1-k where k is a constant.
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document.write( "a, show that P(-1)=0 for any value of k.
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document.write( "b, find all solution to the equation P(x)=0 if k=-1 \n" );
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Algebra.Com's Answer #524959 by math1239028(4)![]() ![]() ![]() You can put this solution on YOUR website! That's an easy one:\r \n" ); document.write( "\n" ); document.write( "a. Just replace where x=-1: \n" ); document.write( "P(-1)=(-1)^3+3(-1)^2+(3-k)(-1)+1-k <=> \n" ); document.write( "P(-1)=-1+3-3+k+1-k=0 => P(-1)=0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "b. for k=-1: P(x)=0 \n" ); document.write( "P(x)=x^3+3x^2+4x+2=0 \n" ); document.write( "And then you solve this equation: \n" ); document.write( "x^3+3x^2+4x+2=0 \n" ); document.write( "(x+1)(x^2+2x+2)=0 \n" ); document.write( "x+1=0 or (x+1)^2=-1 \n" ); document.write( "x=-1 or x+1=i or x+1=-i \n" ); document.write( "____or x=-1+i or x= -1-i\r \n" ); document.write( "\n" ); document.write( "So, summing up, P(x)=0 if k=-1, for x=-1 or x=-1+i or x=-1-i. \n" ); document.write( " |