Point [tex]$A$[/tex] is located at [tex]$(2,6)$[/tex], and point [tex]$M$[/tex] is located at [tex]$(-1,8)$[/tex]. If point [tex]$M$[/tex] is the midpoint of [tex]$\overline{AB}$[/tex], find the location of point [tex]$B$[/tex].

A. [tex]$(5,4)$[/tex]
B. [tex]$(0.5,7)$[/tex]
C. [tex]$(0,6)$[/tex]
D. [tex]$(-4,10)$[/tex]



Answer :

To find the location of point [tex]\( B \)[/tex], let's use the midpoint formula. The midpoint [tex]\( M \)[/tex] of a line segment [tex]\(\overline{AB}\)[/tex] with endpoints [tex]\(A(x_1, y_1)\)[/tex] and [tex]\(B(x_2, y_2)\)[/tex] is given by:

[tex]\[ M = \left(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\right) \][/tex]

Given:
- Point [tex]\( A \)[/tex] is located at [tex]\((2, 6)\)[/tex]
- Point [tex]\( M \)[/tex] is located at [tex]\((-1, 8)\)[/tex]

We need to find the coordinates of point [tex]\( B \)[/tex].

Let's denote point [tex]\( B \)[/tex] as [tex]\((x_2, y_2)\)[/tex].

The formula gives us two equations, one for the x-coordinates and one for the y-coordinates:

[tex]\[ M_x = \frac{x_1 + x_2}{2} \][/tex]
[tex]\[ M_y = \frac{y_1 + y_2}{2} \][/tex]

Substitute the given coordinates of [tex]\(A\)[/tex] and [tex]\(M\)[/tex]:

[tex]\[ -1 = \frac{2 + x_2}{2} \][/tex]
[tex]\[ 8 = \frac{6 + y_2}{2} \][/tex]

We solve for [tex]\(x_2\)[/tex] and [tex]\(y_2\)[/tex] from these equations.

### Solving for [tex]\(x_2\)[/tex]:
Multiply both sides of the equation by 2:

[tex]\[ 2 \cdot -1 = 2 + x_2 \][/tex]
[tex]\[ -2 = 2 + x_2 \][/tex]

Subtract 2 from both sides:

[tex]\[ x_2 = -4 \][/tex]

### Solving for [tex]\(y_2\)[/tex]:
Multiply both sides of the equation by 2:

[tex]\[ 2 \cdot 8 = 6 + y_2 \][/tex]
[tex]\[ 16 = 6 + y_2 \][/tex]

Subtract 6 from both sides:

[tex]\[ y_2 = 10 \][/tex]

Thus, the coordinates of point [tex]\( B \)[/tex] are [tex]\((-4, 10)\)[/tex].

So, the correct location of point [tex]\( B \)[/tex] is:

[tex]\[ \boxed{(-4, 10)} \][/tex]