Explanation:
(Ax² + Bx + C)²
= (Ax² + Bx + C)(Ax² + Bx + C)
= Ax⁴ + 2ABx³ + 2ACx² + 2BCx + C².
By Comparing Coefficients, we have:
A = 1
2AB = 6
2AC = 7
2BC = a
C² = b
Solving them we get A = 1, B = 3 and C = 3.5.
Therefore a = 2BC = 2(3)(3.5) = 21,
b = C² = (3.5)² = 12.25.