Easy
1 point
ID: #26705
Question
a+b = 11, a-b = 7 হলে ab = কত?
Options
1
15
Correct Answer
2
16
Correct Answer
3
12
Correct Answer
4
18
Correct Answer
Explanation
আমরা জানি, ab = {(a+b)/2}² - {(a-b)/2}²। মান বসিয়ে পাই, ab = (11/2)² - (7/2)² = 121/4 - 49/4 = 72/4 = 18। অথবা, 2a=18 (যোগ করে), a=9; 2b=4, b=2; ab=18।
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