Question

(7+m)3
expand.
lesson name equation

Answer 1

21 + 3m = 0
3m = -21
so, m = -21/3 = -7

Answer 2

(7 + m)³

By using formula => a³ + 3a²b + 3ab² + b³

$\therefore{}$ (7 + m)³ = (7)³ + 3 × (7)² × (m) + 3 × (7) × (m)² + (m)³


= 343 + 147m + 21m² + m³