Answer:
Answer: x=2 (third option)
Step-by-step explanation:
Equation of a line
Being m is the slope and (h,k) is a point through which the line passes, the point-slope form of the equation of a line is:
y - k = m ( x - h )
We have the function f passes through the point (-1,9) and has a slope of m=-3. The point-slope equation of the line is:
y - 9 = -3 ( x - (-1) )
Operating:
y - 9 = -3 ( x + 1 )
y - 9 = -3x - 3
Adding 9:
y = -3x + 6
To calculate the zero of the function we set y=0 and solve for x:
-3x + 6 = 0
Subtracting 6:
-3x = - 6
Dividing by -3
x = - 6 / ( - 3 )
x = 2
Answer: x=2 (third option)