Question Video: Writing Algebraic Expressions Mathematics • First Year of Preparatory School

Video Transcript

Write an algebraic expression for the perimeter of the triangle below.

We begin by recalling that the perimeter of a triangle is the sum of all its side lengths. We note that the base of the triangle has a length that is the sum of two 𝑏 and five 𝑐, written two 𝑏 plus five 𝑐. We can add all of the side lengths together to get nine 𝑎 plus two 𝑏 plus five 𝑐 plus 10. Since addition is associative and we can add these values in any order, we can remove the parentheses as shown. Hence, the perimeter of the triangle is nine 𝑎 plus two 𝑏 plus five 𝑐 plus 10.