Final answer:
The question involves geometry, focusing on the proof composition method. We begin with the given information, apply substitution to find the value of 'x', and eventually prove that AB = 6 through a series of algebraic steps.
Step-by-step explanation:
The subject of this question is Mathematics, specifically, proof composition in geometry. Here is the complete proof:
- BC = 5
Reason: Given - 2x + 1 = 5
Reason: Substitution Property (Since BC is given to equal 5, and we have the expression 2x + 1 equal to BC, we can substitute) - 2x = 4
Reason: Subtraction Property of Equality (Subtracting 1 from both sides of the equation) - x = 2
Reason: Division Property of Equality (Dividing both sides of the equation by 2) - AB = 3x
Reason: Given - AB = 3(2)
Reason: Substitution Property (Substituting the value of x into the expression for AB) - AB = 6
Reason: Simplify (Multiplying 3 by 2 gives us 6)