Question 1088722
First remember the formula: (x+a)^2 = x^2 + 2ax + a^2.

so (x+1)^2 = x^2 + 2x + 1.

using this on x^2 + 2x  = 17
   
(x+1)^2 - 1 = 17

(x+1)^2 = 18

abs(x+1) = sqrt(18) = 3sqrt(2)

so x = -1 +3sqrt(2) or x = -1 -3sqrt(2)

aproaching to the nearest hundreth:

x={3.24;-5.24}

@natolino_