JAMB Mathematics 2023 Paper

First, we find the equation of the boundary line using the two intercepts.The slope is

m = $\frac{4-0}{0-5} = \frac{4}{5}$

The y-intercept is 4

The slope-intercept form of the equation is therefore

y = -$\frac{4}{5} x + 4$

$\implies y + \frac{4}{5} x = 4$

Multiply both sides by $\frac{5}{4}$

$\implies \frac{5}{4}\left(y + \frac{4}{5} x\right) = 4 \times \frac{5}{4}$

$\implies \frac{5}{4} y + x = 5$

Multiply both sides by 4

⇒ $5y + 4x = 20$

The inequality is therefore either $5y + 4x \leq 20$ or $5y + 4x \geq 20.$

Using the test point (0, 0) -The origin

⇒ 5(0) + 4(0) ≤ 20

⇒ 0 ≤ 20 (True)

∴ The inequality is $5y + 4x \leq 20$