If `x * y = (x + 3)^2(y-1)`, then find the value of `5` * `4`

If x = 1, y = 2, z = 5 , then find the value of 3x – 2y + 4z.

If 4x + 3y = 25 and 5x + 2y = 26 , then find the values of x and y

(a) If x : y = 3 : 4 , then find the value of the ratio (2x + y) : ( 9x - 2y) . (b) If x : y = 5 : 4 , then find the value of the ratio (x^(2) + xy) : (x^(2) - xy) .

If x = 5/4 and y=(-1)/3 , then find the value of (x + y) xx (x-y) .

If 4x-5y=37 and 3x-4y=25, then find the value of x-y.

If 5x^(2) + 4xy + y^(2) + 2x + 1= 0 then find the value of x, y

(i) x+2y=-7 and 3x-2y=-1, then find the value of x. (ii) If x+y=8 and 4y-x=2, then find the value of y. (iii) If 3x+5y=9 and 5x+3y=7, then find the value of x+y. (iv) If 3x-y=11 and x-3y=17, then find the value of x-y.

If x ,y in R and x^2+y^2+x y=1, then find the minimum value of x^3y+x y^3+4.

If x ,y in R and x^2+y^2+x y=1, then find the minimum value of x^3y+x y^3+4.