Which protocol is used by IP to guarantee the delivery

Find the value of the given expression-

(4^x+4 -5× 4^x+2) / 15×4^x – 2²×4^x

If x² – 10x + 20 = 0, then find the value of (x – 3)² + 1/(x – 3)²

If x + y = 4 and (1/x) + (1/y) = 24/7, then the value of (x³ + y³).

If x, y and z are real numbers such that (x-5)²+(y-8)²+(z-12)²= 0 then (x+y+z) is equal to

If x + y = 12 and x² + y² = 74, find xy.

If p = 27 - q - r and pq + r(q + p) = 168, then find the value of (p² + q² + r²).

If (x + y) = 6 and (x² + y²) = 20, then the value of (x – y)² is equal to:

If x:y:z = 3:4:6, and (5x + 3z) = 132, then find the value of '3y'.