Given that x² + 4x + k = (x + r)² + 1, find the value of k and r.

Correct Answer is : k = 5, r = 2

Correct Answer is : k = 5, r = 2

Test Index

WAEC Further Mathematics 2015 Paper

Question : 19

Total: 40

Given that

x^{2} + 4x + k = (x + r)^{2} + 1

, find the value of k and r.

Solution:

$x^{2} + 4x + k = (x + r)^{2} + 1$

$x^{2} + 4x + k = x^{2} + 2rx + r^{2} + 1$

Comparing the LHS and RHS equations, we have

$2r = 4 \implies r = 2$

$k = r^{2} + 1 = 2^{2} + 1 = 5$

Go to Question:

Prev Question

Next Question