Answer:
<em>a(-5,-2)</em>
Step-by-step explanation:
<u>The midpoint of a segment</u>
Given points C(xc,yc) and B(xb,yb), the coordinates of the midpoint M can be found knowing that:
![\overline{CM} = \overline{ MB}](https://tex.z-dn.net/?f=%5Coverline%7BCM%7D%20%3D%20%5Coverline%7B%20MB%7D)
Applying that relation in both axes separately, we can write:
![\displaystyle x_m=\frac{xc+xb}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20x_m%3D%5Cfrac%7Bxc%2Bxb%7D%7B2%7D)
![\displaystyle y_m=\frac{yc+yb}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20y_m%3D%5Cfrac%7Byc%2Byb%7D%7B2%7D)
Knowing the coordinates of the midpoint and B, we can find the coordinates of the other extreme C solving both equations for the required variable:
![x_c=2x_m-x_b](https://tex.z-dn.net/?f=x_c%3D2x_m-x_b)
![y_c=2y_m-y_b](https://tex.z-dn.net/?f=y_c%3D2y_m-y_b)
Plugging in the known values: M=(-1,1) and B=(3,4):
![x_c=2*(-1)-3=-2-3=-5](https://tex.z-dn.net/?f=x_c%3D2%2A%28-1%29-3%3D-2-3%3D-5)
![y_c=2*1-4 = 2-4=-2](https://tex.z-dn.net/?f=y_c%3D2%2A1-4%20%3D%202-4%3D-2)
The coordinates of C are (-5,-2)
a(-5,-2)