Question

The binary operation $\ast$ : R $\times$ R $\to$ R is defined as a $a\ast b=2a+b$. Find $(2\ast 3)\ast 4$.

Answer 1

Given $:a\ast b=2a+b$

$\Rightarrow (2\ast 3)=2\left(2\right)+3=7$

$\Rightarrow (2\ast 3)\ast 4=\left(7\right)\ast 4=2\left(7\right)+4=18$