a) (x+2)^2-(x-5)(x+1)=17
(=)x²+4x+4-x²-x+5x+5=17
(=)(x²-x²)+(4x+5x-x)+(5+4)=17
(=)8x+9=17
(=)8x=17-9
(=)8x=8
(=)x=1
S={1}
b) x^2 +5x=2(x+5
(=)x(x+5)=2(x+5)
(=)x(x+5)-2(x+5)=0
(=)(x-2)(x+5)=0
(=)\(\left[ \begin{array}{l}x-2=0\\x+5=0\end{array} \right.\) (=)\(\left[ \begin{array}{l}x=2\\x=-5\end{array} \right.\)
S={2;-5}