Answer:
12x² - 6; 21 inches ⇒ A
Step-by-step explanation:
Let us solve the question
∵ The side lengths of a triangle are 4x² - 3 in., 4x² - 2 in., 4x² - 1 in.
∴ S1 = 4x² - 3 inches
∴ S2 = 4x² - 2 inches
∴ S3 = 4x² - 1 inches
→ The perimeter of the triangle is the sum of the lengths of its 3 sides
∵ P = S1 + S2 + S3
∴ P = 4x² - 3 + 4x² - 2 + 4x² - 1
→ Add the like terms
∵ P = (4x² + 4x² + 4x²) + (-3 + -2 + -1)
∴ P = 12x² + -6
→ Remember (+)(-) = (-)
∴ P = 12x² - 6
∴ The expression of the perimeter of the Δ is 12x² - 6
∵ x = 1.5
→ Substitute x in the perimeter expression by 1.5
∵ P = 12(1.5)² - 6
∴ P = 12(2.25) - 6
∴ P = 27 - 6
∴ P = 21 inches
∴ The perimeter of the triangle is 21 inches
The expression can be used to find the perimeter of the triangle is 12x² - 6 and its perimeter is 21 inches when x = 1.5
