CUET Preparation Today
If a2 + b2 = 8, x2 + y2 = 5, ax + by = 2, then find ay - bx. |
6 7 8 9 |
6 |
Here note the result : If ax + by = m, and ay - bx = n then (a2 + b2)(x2 + y2) = m2 + n2 Therefore, using this result ⇒ (8) (5) = 22 + n2 ⇒ (8 × 5) - 4 = n2 ⇒ n2 =40 - 4 = 36 ⇒ n = \(\sqrt {36}\) = 6 |
