Question:
Solve each of the following system of equations in R.
14. $5 x-7<3(x+3), 1-\frac{3 x}{2} \geq x-4$
Solution:
$5 x-7<3(x+3)$
$\Rightarrow 5 x-7<3 x+9$
$\Rightarrow 5 x-3 x<9+7$
$\Rightarrow 2 x<16$
$\Rightarrow x<8$
$\Rightarrow x \in(-\infty, 8) \quad \ldots(\mathrm{i})$
Also, $1-\frac{3 x}{2} \geq x-4$
$\Rightarrow x-4 \leq 1-\frac{3 x}{2}$
$\Rightarrow x+\frac{3 x}{2} \leq 1+4$
$\Rightarrow \frac{2 x+3 x}{2} \leq 5$
$\Rightarrow 5 x \leq 10$
$\Rightarrow x \leq 2$
$\Rightarrow x \in(-\infty, 2] \quad \ldots$ (ii)
Hence, the solution of the given set of inequalities is the intersection of (i) and (ii).
$(-\infty, 8) \cap(-\infty, 2]=(-\infty, 2]$
Hence, the solution of the given set of inequalities is $(-\infty, 2]$.