An optical device Y has a positive focal length. Y

If 27 (x+y)³ − 8(x−y)³ = (x + 5y) (Ax² + By² + Cxy), then what is the value of (A+B-C)?

If a + b + c = 5, a³ + b³ + c³ = 85 and abc =25, then find the value of a² + b² + c² – ab –bc – ca

What is the highest common factor of (x³ - x² - x - 15) and (x³ - 3x² - 3x + 9)?

If (3x - y) = 3, xy = (2/3), then find the value of {x³ - (y³/27)}

(u - 5) ² + (v + 2) ² + (w – 4) ² = 0, then find the value of 4u - v + w.

If (6m – 5n) ²  = 7 and 30mn = 60, then find the value of (6m + 5n) ²  + 16mn.

If x² + y² + z² = xy + yz + zy (x≠0), then the value of (5x+3y-4z)/2x is

If ab = -15 and (a² + b²) = 34, then find the value of (a – b).

If (528 – 507 + 195) ÷ 11 + √1296 = x, then {(x/2) + 10} = ?

If 9x² + 16y² = 24xy, then find the ratio of ‘x’ and ‘y’, respectively.