23. x x1y1 + y. 24. x3 — x2y\ + x3y‡ — xy + xły‡ – y§. 25. } √15, # √7, } $175. 26. 3 (2 — √3), § (3 √2 − 2√3), † ( √5 +. √ 3). 27. (2 + √2 - √6), ¿ (2 √3 + 3 √2 - √30), 5 + 2 √6. 28. a (x2 - x2y3 's (3 - 32. 2 + 3. 23 – 3.2 + 3§. 2§ – 2§), b − xżył + y). 30. √6 + √2, √6 – √3, √√ 15 – √5. 6. Less than 5 when x lies between 2 and 3; greater than 5 for all values beyond these limits. 8. a satisfies the equation 4202 - (a + b 6 c)x + 2 (cab) = 0. 2. From 0° to 90°, +; from 90° to 180°, — ; from 180° to 270°, +; from 270° to 360°, – and 45°, 45° and 135°, 135° and 225°, 225° and 315° The corresponding signs of cos A respectively. sin A are + +. 4. Cos 2 A is +, -, +, - respectively, as in Question 3. |