If a - b = 5 and $a^2 + b^2 = 45$, then the value of ab is:
Answer & explanation
Correct answer: option 2
(a – b)2 = a2 + b2 – 2ab
= 52 = 45 - 2ab
= 25 = 45 – 2ab
= 2ab = 45 – 25 = 20
= ab = 10
If a - b = 5 and $a^2 + b^2 = 45$, then the value of ab is:
Correct answer: option 2
(a – b)2 = a2 + b2 – 2ab
= 52 = 45 - 2ab
= 25 = 45 – 2ab
= 2ab = 45 – 25 = 20
= ab = 10