RRB Group-D Model Paper 20 with answers for online practice

Given:
expression:- 3x(x + 4) - x(x - 2)
Calculation:
considering the given expression
3x(x + 4) - x(x - 2)
⇒ $3{\mathit{x}}^2+12\mathit{x}-{\mathit{x}}^2$ + 2x
⇒ $3{\mathit{x}}^2-{\mathit{x}}^2$ + 12x + 2x
⇒ $2{\mathit{x}}^2$ + 14x
∴ required value = $2{\mathit{x}}^2$ + 14x