a + b = 9 এবং a - b = 7 হলে ab -এর মান কত ?
Correct Answer: Option B
1st method \(ab = (\frac{{a + b}}{2})2 - (\frac{{a - b}}{2})2 = (\frac{9}{2})2 - (\frac{7}{2})2\) = (4.5)2 - (3.5)2 = 20.25 - 12.25 = 8
ab = 8
2nd method
a = 9+7 = 16 \( \div \) 2 = 8 b = 9-7 = 2 \( \div \) 2 = 1 ab = 8\( \times \) 1 = 8
Download our app for free and access thousands of MCQ questions with detailed solutions