document.write( "Question 168096: I'm Having hard time solving this homework. Can anyone help?\r
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\n" ); document.write( "\n" ); document.write( "2. Calculate the points of the tangent of the curve : y = ex(x2 – 8) where and in which the tangent line is horizontal\r
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\n" ); document.write( "\n" ); document.write( "3. Write one of the two tangents to the curve : y = 1 + x³ which are parallel to this equation 12x - y = 1.\r
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\n" ); document.write( "\n" ); document.write( "4. Calculate\r
\n" ); document.write( "\n" ); document.write( "I) If f(x) = ex cos x calculate f ’(x) et f ’’\r
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\n" ); document.write( "\n" ); document.write( "(ii) Calculate (d99/ dx99) Sin x\r
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\n" ); document.write( "\n" ); document.write( "5.\r
\n" ); document.write( "\n" ); document.write( "Calculate the derivative :\r
\n" ); document.write( "\n" ); document.write( " I) y = xe-x²\r
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\n" ); document.write( "\n" ); document.write( "II) Let say: r(x) = f(g(h(x))) whit h(1) = 2, g(2) = 3, h’(1)= 4, g’(2) = 5, f’(3) = 6. Calculate r’(1).\r
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\n" ); document.write( "\n" ); document.write( "III) Show that the function : y = Ae-x + Be-x satisfy the equation with differential y”+ 2y’+y = 0\r
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Algebra.Com's Answer #123882 by oscargut(2103)\"\" \"About 
You can put this solution on YOUR website!
Hi here i answered questions 2) and 3) contact me if you need more help\r
\n" ); document.write( "\n" ); document.write( "2. Calculate the points of the tangent of the curve : y = ex(x2 – 8) where and in which the tangent line is horizontal\r
\n" ); document.write( "\n" ); document.write( "\"y=exp%28x%5E2-8%29\" ,\"dy%2Fdx=2x%2Aexp%28x%5E2-8%29\"\r
\n" ); document.write( "\n" ); document.write( "y'=0 if only if x=0\r
\n" ); document.write( "\n" ); document.write( "then the point is (0,0) (where the tangent of the curve is horizontal)\r
\n" ); document.write( "\n" ); document.write( "3. Write one of the two tangents to the curve : y = 1 + x³ which are parallel to this equation 12x - y = 1.\r
\n" ); document.write( "\n" ); document.write( "\"12x-y=1\"
\n" ); document.write( "then
\n" ); document.write( "\"y+=+12x-1\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+1%2Bx%5E3\" then \"dy%2Fdx=3x%5E2\"\r
\n" ); document.write( "\n" ); document.write( "then 12 (first term of 12x-1 and y'(x)= 3x^2 are the same}\r
\n" ); document.write( "\n" ); document.write( "\"12+=+3x%5E2\" then \"x%5E2=4\" then \"x=2\" or \"x=-2\"\r
\n" ); document.write( "\n" ); document.write( "taking x=2 then equation of the line is \"y+=+%28dy%2Fdx%29%2A%282%29%28x-2%29%2By%282%29\" where \"y%28x%29=1%2Bx%5E3\"\r
\n" ); document.write( "\n" ); document.write( "then line is \"y+=+12%28x-2%29%2B9=12x-15\"\r
\n" ); document.write( "\n" ); document.write( "Answer: \"y+=+12x-15\" \r
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