Practicing Success
If x4 + x2y2 + y4 = 273 x2 - xy + y2 = 13, then find xy. |
2 6 4 8 |
4 |
Formula → x4 + y4 + x2y2 = (x2 + y2 + xy) × (x2 + y2 - xy) ⇒ 273 = 13 × (x2 + y2 + xy) ⇒ x2 + y2 + xy = \(\frac{273}{13}\) ⇒ x2 + y2 + xy = 21 ............(i) ⇒ x2 + y2 - xy = 13 (given) .............(ii) (i) - (ii), ⇒ 2xy = 8 ⇒ xy = 4 |