Find the fourth proportional of 4x, x + 4, 3x –1, if x

The sum of two numbers is 45 and their difference is 9. What is the larger number?

If a³ + b³ = 6240 and a + b = 30, then find the value of {(a + b)² – 3ab}

 If f(x) = 3x² − 7x + 5, find f(2a) − 4f(a).

If, ( a + b = 20 ) and ( a² + b² = 208 ), then find the value of (a³ + b³).

If x² – 8√2x + 1 = 0, then what is the value of x³ + 1/x³.

If (5x - 2y) = 170 and 4x:3y = 32:9, then find the value of (3x² + y²).

Solve for x:

(2x − 1)/3 − (x − 4)/2 = 3

If (8x - 3y) = 196 and 7x:4y = 35:16, then find the value of (x² + 4y²).