We know that
point A(1,1) C(3,5)
point D(-2,-4) F(0,0)
step 1
find the slope FD
m=(y2-y1)/(x2-x1)------> m=(0+4)/(0+2)----> m=4/2----> m=2
step 2
find the slope AC
m=(y2-y1)/(x2-x1)------> m=(5-1)/(3-1)----> m=4/2-----> m=2
mAC=mFD
the answer is
the slope FD is 2
15.6 in 13 minutes? are you asking how it got to 15.6 in 13 minutes?
The third table
Explanation:
6/4 = 1.5 , 9/6 = 1.5 , 12/8 = 1.5
Remember
a²-b²=(a-b)(a+b)
8x²-50y²
2(4x²-25y²)
(2)([2x]²-[5y]²)
2(2x-5y)(2x+5y)