Question

Multiply. {}=3\dfrac{1}{2} \times 3\dfrac12=3 2 1 ​ ×3 2 1 ​

Answer 1

I assume you mean the product of mixed numbers,

3 1/2 × 3 1/2

If we write this as

(3 + 1/2) × (3 + 1/2) = (3 + 1/2)²

we can use the identity

(a + b)² = a² + 2ab + b²

so that

3 1/2 × 3 1/2 = 3² + (2 × 3 × 1/2) + (1/2)²

3 1/2 × 3 1/2 = 9 + 3 + 1/4

3 1/2 × 3 1/2 = 12 1/4

Alternatively, we can first write 3 1/2 as a mixed number:

3 + 1/2 = 6/2 + 1/2 = (6 + 1)/2 = 7/2

Then

3 1/2 × 3 1/2 = 7/2 × 7/2 = (7 × 7) / (2 × 2) = 49/4

and

49/4 = (48 + 1)/4 = ((4 × 12) + 1)/4 = 12 + 1/4