Question

If BC = 5x - 9 and AB = 2x + 21, find the value of x.

Answer 1

Suppose that B is the midpoint of segment AC; therefore, AB=BC

Thus,

$\begin{gathered} AB=BC \\ \Rightarrow2x+21=5x-9 \end{gathered}$

Solve for x as shown below

$\begin{gathered} \Rightarrow3x-9=21 \\ \Rightarrow3x=30 \\ \Rightarrow x=10 \end{gathered}$

Therefore, the answer is x=10