Bonsoir ;
1)
[tex]f'(x) = \frac{(1-2x)'(x+3)-(1-2x)(x+3)'}{ (x+3)^{2} } = \frac{x-2(x+3)-(1-2x)}{(x+3)^{2}} \\ \\ = \frac{-2x-6-1+2x}{ (x+3)^{2} } = -\frac{7}{(x+3)^{2} } .[/tex]
2)
[tex]f'(x) = (1-2x)'(-3x^2 +5)+(1-2x)(-3x^2+5)' \\ \\ = -2(-3x^2+5)-6x(1-2x) = 6x^2-10-6x+12x^2 \\ \\ = 18 x^{2} -6x - 10 .[/tex]
