Question

1. Find the distance between (-10,1), (-9,8)
A. 2√70
B. 5√2
C. 4√3
D. 2√41


2. Find the midpoint of (-3,5) and (4,-9)
A. (-2, 1/12)
B. (-1/2, 2)
C. (2, -1/2)
D. (1/12, -2)


3. If R is the midpoint of QS, find QS.
x=?
QS=?

Answer 1

Answer:

#1

Use distance formula:

• $d = \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$
• $d = \sqrt{(-9+10)^2+(8-1)^2} =\sqrt{1+49} =\sqrt{50} =5\sqrt{2}$

Correct choice is B

#2

Use midpoint formula:

• $x = (x_1+x_2)/2, y = (y_1+y_2)/2$
• $x = (-3 +4)/2 = 1/2\\y=(5-9)/2=-4/2=-2$

Correct choice is D, it should read (1/2, -2)

#3

R is midpoint of QS:

• QR = RS
• 2x + 16 = 5x - 17
• 5x - 2x = 16 + 17
• 3x = 33
• x = 11
• QS = 2(2x + 16) = 2(2*11 + 16) = 2(38) = 76