If 2a + 5b = 12 and ab = 3, find the value of $4a^2 + 25b^2$ ?
Answer & explanation
Correct answer: option 3
If 2a + 5b = 12
ab = 3,
find the value of $4a^2 + 25b^2$ = ?
we know that,
If $K+l=n$
then, $K^2+l^2$ = n2 – 2 × k × l
The value of $4a^2 + 25b^2$= 122 – 2 × 3 × 2 × 5 = 144 - 60 = 84