JAMB - Mathematics (1992 - No. 16)
Find all values of x satisfying the inequality -11 \(\leq\) 4 - 3x \(\leq\) 28
-5 \(\leq\) x \(\geq\) 8
5 \(\leq\) x \(\leq\) 8
-8 \(\leq\) x \(\leq\) 5
-5 < x \(\leq\) 8
Explanation
To solve -11 \(\leq\) 4 - 3x \(\leq\) 28
-11 \(\leq\) 4 - 3x also 4 -3x \(\leq\) 28
- 11 - 4\(\leq\) - 3x and -3x \(\leq\) 28 - 4
-15\(\leq\) -3x and -3x \(\leq\) 24
i.e. x \(\leq\) 5 and x \(\geq\) -8
∴ -8 \(\leq\) x \(\leq\) 5
-11 \(\leq\) 4 - 3x also 4 -3x \(\leq\) 28
- 11 - 4\(\leq\) - 3x and -3x \(\leq\) 28 - 4
-15\(\leq\) -3x and -3x \(\leq\) 24
i.e. x \(\leq\) 5 and x \(\geq\) -8
∴ -8 \(\leq\) x \(\leq\) 5
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