Answer:
6
Step-by-step explanation:
We want to expand this; (x + y)⁴
This can be written as;
(x + y)² × (x + y)²
This gives;
(x² + 2xy + y²) × (x² + 2xy + y²)
This gives;
x²(x² + 2xy + y²) + 2xy(x² + 2xy + y²) + y²(x² + 2xy + y²) = x⁴ + 2x³y + x²y² + 2x³y + 4x²y² + 2xy³ + x²y² + 2xy³ + y⁴
Simplifying gives;
x⁴ + 4x³y + 4xy³ + 6x²y² + y⁴
Thus, the coefficient of x²y² is 6
