document.write( "Question 1159638: The line y=2x+c is a tangent to the curve y=2x^2-6x+20.find the value of c \n" ); document.write( "

Algebra.Com's Answer #782676 by math_helper(2461) $\"\"$ $\"About$

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document.write( "f'(x) = \r
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document.write( "For the tangent  to just touch f(x), we need to find where f(x) has slope equal to 2:\r
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document.write( "    4x-6 = 2     <<< remember, the ENTIRE LHS is the slope of f(x)
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document.write( "     x = 2        \r
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document.write( "At x=2:  f(2) = \r
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document.write( "So the tangent line  just meets f(x) at x=2, hence it has value 16 there:\r
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document.write( "     2x + c = 2(2) + c = 16  ==> c = 12\r
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document.write( "Ans:    and the tangent line is  y=2x+12, and the point of tangency is (2,16).
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