
We know that

because of the Pythagorean trig identity

.
Since the slope is -2 because
x1: -1 x2: 0
y1: 2 y2: 0
y2-y1/x2-x1 = slope (0-2/0+1= -2/1 = -2)
You would havr to change it into point slope form so it would look like this
Y-2 = -2(x+1)
y-2 = -2x -2
+2 +2
y = -2x + 0
Hope this helps:)
Write a recursive and explicit formula for each option.
Save a nickel on the first day of the month and then double the amount each day for a month
=> a1 =0.05
=> a2 = a1* 2 = 0.05*2
=> a3 = a2*2 = a1* 2*2
..............................................
=>recursive an =
=> explicit an = 0.05*
Start their savings by saving $10 on the first day and then $10 each day of the month
=> a1 = 10
=> a2 = a1 + 10 = 20
=> a3 = a2 +10 = 20 +10 =30
........................................................
=> recursive an = 
=> explicit an = 10 + 10( n-1)
Hope it will find you well.
For b it's 39 because you multiply 5 and 7 giving you 35 then add 4 Wich equals 39. I might be incorrect. check it out.