If a + b = 7 and ab = 10, what is a² + b²?
Correct answer: A. 29
Use (a + b)² = a² + 2ab + b². So 49 = a² + b² + 20, and a² + b² = 29. Check with a = 5 and b = 2: 25 + 4 = 29. This identity often saves solving for a and b separately.
hard
Answer and explanation
The correct answer is A. 29
Use (a + b)² = a² + 2ab + b². So 49 = a² + b² + 20, and a² + b² = 29. Check with a = 5 and b = 2: 25 + 4 = 29. This identity often saves solving for a and b separately.
Topic: Algebra and Equations MCQs · Subject: Numerical Ability