document.write( "Question 1013112: Given f(-1)=3 and f(2)=9, write a function in the form f(x)=mx+b. I have no idea where to start with this question... \n" ); document.write( "
Algebra.Com's Answer #629275 by macston(5194)\"\" \"About 
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Using y for f(x):
\n" ); document.write( "when x=-1, y=3
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\n" ); document.write( "y=mx+b
\n" ); document.write( "3=-m+b
\n" ); document.write( "b=3+m Use this to substitute for b below.
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\n" ); document.write( "When x=2, y=9
\n" ); document.write( "y=mx+b
\n" ); document.write( "9=2m+b Substitute for b from above.
\n" ); document.write( "9=2m+(3+m)
\n" ); document.write( "9=3m+3
\n" ); document.write( "6=3m
\n" ); document.write( "2=m
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\n" ); document.write( "b=3+m=3+2=5
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\n" ); document.write( "y=mx+b
\n" ); document.write( "y=2x+5
\n" ); document.write( "ANSWER: f(x)=2x+5
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\n" ); document.write( "CHECK:
\n" ); document.write( "f(-1)=2(-1)+5
\n" ); document.write( "3=-2+5
\n" ); document.write( "3=3
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\n" ); document.write( "f(2)=2(2)+5
\n" ); document.write( "9=4+5
\n" ); document.write( "9=9
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