WAEC 2016 Mathematics · Question 2

The relation y = x2 + 2x + k passes through the point (2,0). Find the value of k

Options

A.- 8
B.- 4
C.4
D.8

Answer: A. - 8

Explanation written with AI and checked against the answer key

Analyze the question: The curve y = x² + 2x + k passes through the point (2, 0). That means when x = 2, y = 0. We substitute these values to find k. Concept: If a point lies on a curve, its coordinates satisfy the equation of the curve. Solution: Substitute x = 2 and y = 0 into y = x² + 2x + k: 0 = (2)² + 2(2) + k 0 = 4 + 4 + k 0 = 8 + k k = −8 Check: With k = −8, y = x² + 2x − 8. At x = 2: 4 + 4 − 8 = 0 ✓ Tip: In "passes through the point (a, b)" questions, always replace x with a and y with b, then solve for the unknown. Always check by substituting your answer back into the equation. Also watch the signs: since 8 + k = 0, k must be the negative of 8.

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