If the slope of a line is -2 and its y-intercept is -7, the equation of the line is:

1. 2x + y + 7 = 0

2. 2x - y + 7 = 0

3. 2x - y - 7 = 0

4. 2x + y - 7 = 0

slope = -2 ⇒ m = -2

y-intercept = -7 ⇒ c = -7

∴ Equation is : y = mx + c

⇒ y = (-2)x + (-7)

⇒ y = -2x - 7

⇒ 2x + y + 7 = 0

Hence, option 1 is the correct option.