Question:
Solve each of the following system of equations in R.
10. 11 − 5x > −4, 4x + 13 ≤ −11
Solution:
We have,
$11-5 x>-4$
$\Rightarrow-5 x>-4-11$
$\Rightarrow-5 x>-15$
$\Rightarrow 5 x<15 \quad$ [Multiplying both sides by $-1$ ]
$\Rightarrow x<\frac{15}{5}$
$\Rightarrow x<3$
$\Rightarrow x \in(-\infty, 3) \quad \ldots$ (i)
Als $o, 4 x+13 \leq-11$
$\Rightarrow 4 x \leq-11-13$
$\Rightarrow 4 x \leq-24$
$\Rightarrow x \leq-6$
$\Rightarrow x \in(-\infty,-6] \quad \ldots$ (ii)
Hence, the solution of the given set of inequalities is the intersection of (i) and (ii).
$(-\infty 3) \cap(-\infty,-6]=(-\infty,-6]$
Hence, the solution of the given set of inequalities is $(-\infty,-6]$.