Which formula should be used to find the slope of
EF?

A) x = -
b ± b2 - 4ac
2a
B) m =
y2 - y1
x2 - x1
C) m =
y2 + y1
x2 + x1
D) M = (
x1 + x2
2
,
y1 + y2
2
)

Step-by-step explanation:

A) The formula x =  -b ± sqrt(b2 - 4ac)/2a calculates the roots of a quadratic equation.

D) The formula M = ((x1 + x2)/2, (y1 + y2)/2) calculates the mid-point of the line joining the points  and .

B) The formula m = ((y2 - y1)/(x2 - x1)) calculates the slope of a line.

Hence, option B should be used to find the slope of EF.