document.write( "Question 1088882: In the xy plane, the point (-1,2) is the minimum of the quadratic function f(x)=x^2+ax+b. What's the absolute value of a-2b? \n" ); document.write( "

Algebra.Com's Answer #703217 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "If it's the minimum value, then it's the vertex.
\n" ); document.write( " $\"f%28x%29=%28x%2B1%29%5E2%2B2\"$
\n" ); document.write( " $\"f%28x%29=x%5E2%2B2x%2B1%2B2\"$
\n" ); document.write( " $\"f%28x%29=x%5E2%2B2x%2B3\"$ \r
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\n" ); document.write( "\n" ); document.write( "So then a = 2, b = 3\r
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\n" ); document.write( "\n" ); document.write( "a - 2b = 2 - 2*3 = 2 - 6 = -4.\r
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\n" ); document.write( "\n" ); document.write( "Absolute value of (a-2b) is 4.\r
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