Question

Solve this : (x + 1)( x + 2)( x + 3)( x + 4 ) - 840 = 0

Answer 1

$(x + 1)(x + 2)(x + 3)(x + 4) - 840 = 0 \\ x(1 + 2 + 3 + 4) = 0 - 840 \\ x(10) = - 840 \\ x \times 10 = - 840 \\ x = - 840 \div 10 \\ x = - 84$