College of Admission Tests Multan

Algebra

Solve the question of and select the option from the choices A through D/E. Check your Answer and view the explanation.

Question: 6

If a - b = 3 and a2 + b2 = 29, find the value of ab.
  • 10
  • 12
  • 15
  • 18

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Correct Answer: A

If a - b = 3 and a2 + b2 = 29, find the value of ab.

(a - b)2 = a2 + b2 -2ab
Put the values: 32 = 29 - 2ab
-2ab = 9 - 29
-2ab = -20
ab = 10