Verified answer

Answer:

9rn²+4n²+p²+12rn²+4np+6prn

Step-by-step explanation:

(x+y+z)² = x²+y²+z²+2xy+2yz+2zx

(3rn+2n+p)² = (3rn)²+(2n)²+p²+2×3rn×2n+2×2n×p+2×p×3rn

9rn²+4n²+p²+12rn²+4np+6prn