a.
\(\eqalign{ & y' = \left[ {{a \over {a + b}}{x^2} + {b \over {a + b}}x + {c \over {\left( {a + b} \right)x}}} \right] \cr & = {{2a} \over {a + b}}x + {b \over {a + b}} - {c \over {\left( {a + b} \right){x^2}}} \cr & = {{2a{x^3} + b{x^2} - c} \over {\left( {a + b} \right){x^2}}} \cr} \)
b.
\(\eqalign{ & y' = 4{\left( {{x^3} - {1 \over {{x^3}}} + 3} \right)^3}\left( {3{x^2} + {3 \over {{x^4}}}} \right) \cr & = 12\left( {{x^3} - {1 \over {{x^3}}} + 3} \right)\left( {{x^2} + {1 \over {{x^4}}}} \right) \cr} \)
c. \(y' = 3{x^2}{\cos ^2}x - {x^3}\sin 2x = {x^2}\left( {3{{\cos }^2}x - x\sin 2x} \right)\)
d. \(y' = {x \over {\sqrt {4 + {x^2}} }}\cos \sqrt {4 + {x^2}} \)
e.
\(\eqalign{ & y' = {{1 - {1 \over {{x^2}}}} \over {2{{\cos }^2}\left( {x + {1 \over x}} \right)\sqrt {1 + \tan \left( {x + {1 \over x}} \right)} }} \cr & = {{{x^2} - 1} \over {2{x^2}{{\cos }^2}\left( {x + {1 \over x}} \right)\sqrt {1 + \tan \left( {x + {1 \over x}} \right)} }} \cr} \)
