Speed of a motorboat in still water is 50 km per hour if

when x =4 and y =-6 then find the value of 27x³ +58x²y +31xy² +8y³?

If a – b – c = 0, then the value of (a² + b² + c²)/(b + ac) is:

If 2x+1, x+2, 2 and 5 are in proportion, then what is the mean proportional between 3.5(1-x) and 8(1+x)?

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

If x = √7 + √6 and y = √7 - √6 , then the value of is (x² + y²)/(x³ + y³).

If = 2 then find

If 2x + y = 15 and xy = 18, then the value of (4x² - y²)