Find the range of values of x for which 2x² + 7x - 15 ≥ 0.

Correct Answer is : x ≤ -5 or x ≥ 32\;3/223

Correct Answer is : x ≤ -5 or x ≥ 32\;3/223

Test Index

WAEC Further Mathematics 2022 Paper

Question : 36

Total: 45

^2

+ 7x - 15 ≥ 0.

Solution:

Concept:

Solve the quadratic inequality by factorisation and then check the intervals on the number line.

Explanation:

Given:

2x^2 + 7x - 15 \ge 0

Factorise the quadratic:

2x^2 - 3x + 10x - 15 \ge 0

x(2x - 3) + 5(2x - 3) \ge 0

(x + 5)(2x - 3) \ge 0

The critical points are:

x = -5

and

x = \frac{3}{2}

Since the coefficient of

x^2

is positive, the expression is non-negative outside the roots.

Therefore, the solution is:

x \le -5

x \ge \frac{3}{2}

Answer:

x \le -5

x \ge \frac{3}{2}

Go to Question:

Prev Question

Next Question