The side of a square is $(3 a + 2)$ cm. Find its perimeter.

Class 8Algebraic Expressions and IdentitiesAlgebra

Step-by-Step Solution

Perimeter of a square = 4 × side =

4 (3 a + 2) = 12 a + 8

cm. Multiply BOTH terms by 4 — stopping after the first gives

12 a + 2

. The expression

9 a^{2} + 12 a + 4

(3 a + 2)^{2}

, which is the AREA, not the perimeter;

6 a + 4

doubles the side instead of quadrupling it.

Answer: D)

12 a + 8 cm

Use the distributive property — multiply the monomial by EVERY term in the polynomial.

Example:

3 x \times (4 x^{2} - 5 x + 2) = 12 x^{3} - 15 x^{2} + 6 x

.

When multiplying powers of the same variable: **add the exponents**.

x^{2} \times x^{3} = x^{5}

Don't just memorise the answer — build a daily practice habit.