For the quadratic equation x² - 10x - 1000 = 0 is quadratic formula the only way I can solve it?

No, you could also solve it graphically

Step-by-step explanation:

If you put the equation into a graphing calculator (or something like desmos/geogebra) you can also check the points of intersection on the x-axis.

b is the answer that makes most sense

step-by-step explanation:

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18