document.write( "Question 930999: A cubic polynomial function f(x) has leading coefficient -2 and intercepts the y-axis at 2.If f(1)=1, and f(-2) =-2, find f(-1) and write the complete function.
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Algebra.Com's Answer #565402 by MathLover1(20850)\"\" \"About 
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A cubic polynomial function:\r
\n" ); document.write( "\n" ); document.write( "\"+f%28x%29+=ax%5E3%2Bbx%5E2%2Bcx%2Bd\"\r
\n" ); document.write( "\n" ); document.write( "given:
\n" ); document.write( "has leading coefficient \"+-2+\"=>\"highlight%28a=-2%29\"\r
\n" ); document.write( "\n" ); document.write( "so far we know \"+f%28x%29+=-2x%5E3%2Bbx%5E2%2Bcx%2Bd\"\r
\n" ); document.write( "\n" ); document.write( "and intercepts the y-axis at \"2\": => \"highlight%28d=2%29\"=> \"+f%28x%29+=-2x%5E3%2Bbx%5E2%2Bcx%2B2\"\r
\n" ); document.write( "\n" ); document.write( "If \"f%281%29=1\" => \"+f%281%29+=-2%281%29%5E3%2Bb%281%29%5E2%2Bc%281%29%2B2=1\"\r
\n" ); document.write( "\n" ); document.write( "=>\"+-2%2Bb%2Bc%2B2=1\"\r
\n" ); document.write( "\n" ); document.write( "=>\"+b%2Bc=1\".......eq.1\r
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\n" ); document.write( "\n" ); document.write( " and \"f%28-2%29+=-2\" => \"+f%28-2%29+=-2%28-2%29%5E3%2Bb%28-2%29%5E2%2Bc%28-2%29%2B2=-2\"\r
\n" ); document.write( "\n" ); document.write( "=> \"+-2%28-8%29%2Bb%284%29%2Bc%28-2%29%2B2=-2\"\r
\n" ); document.write( "\n" ); document.write( "=>\"16%2B4b-2c%2B2=-2\"\r
\n" ); document.write( "\n" ); document.write( "=>\"+4b-2c=-20\".......eq.2\r
\n" ); document.write( "\n" ); document.write( "solve the system:\r
\n" ); document.write( "\n" ); document.write( "\"+b%2Bc=1\".......eq.1\r
\n" ); document.write( "\n" ); document.write( "\"+4b-2c=-20\".......eq.2
\n" ); document.write( "_________________________\r
\n" ); document.write( "\n" ); document.write( "\"+b%2Bc=1\".......eq.1 ...solve for \"b\"\r
\n" ); document.write( "\n" ); document.write( "\"+b=1-c\"...substitute in eq.2\r
\n" ); document.write( "\n" ); document.write( "\"+4%281-c%29-2c=-20\".......eq.2...solve for \"c\"\r
\n" ); document.write( "\n" ); document.write( "\"+4-4c-2c=-20\"\r
\n" ); document.write( "\n" ); document.write( "\"+4-6c=-20\"\r
\n" ); document.write( "\n" ); document.write( "\"+4%2B20=6c\"\r
\n" ); document.write( "\n" ); document.write( "\"+24=6c\"\r
\n" ); document.write( "\n" ); document.write( "\"+24%2F6=c\"\r
\n" ); document.write( "\n" ); document.write( "\"highlight%28c=4%29\"\r
\n" ); document.write( "\n" ); document.write( "find \"b\"\r
\n" ); document.write( "\n" ); document.write( "\"+b=1-c\"
\n" ); document.write( "\"+b=1-4\"
\n" ); document.write( "\"highlight%28+b=-3%29\"\r
\n" ); document.write( "\n" ); document.write( " the complete function is:\r
\n" ); document.write( "\n" ); document.write( "\"+f%28x%29+=-2x%5E3-3x%5E2%2B4x%2B2\"\r
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\n" ); document.write( "\n" ); document.write( "find \"f%28-1%29\" :\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-1%29+=-2%28-1%29%5E3-3%28-1%29%5E2%2B4%28-1%29%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-1%29+=-2%28-1%29-3%281%29%2B4%28-1%29%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-1%29+=2-3-4%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-1%29+=-3\"\r
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\n" ); document.write( "\n" ); document.write( "check:
\n" ); document.write( "\"+f%28-2%29+=-2%28-2%29%5E3-3%28-2%29%5E2%2B4%28-2%29%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-2%29+=-2%28-8%29-3%284%29%2B4%28-2%29%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-2%29+=16-12-8%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-2%29+=4-8%2B2\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-2%29+=6-8\"\r
\n" ); document.write( "\n" ); document.write( "\"+f%28-2%29+=-2\"...as given\r
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