Question

3x+4y=17 and xy=3 find 27x^3+64y^3

Answer 1

Answer:

3077

Step-by-step explanation:

(3x + 4y)^3 = 27x^3 + 64y^3 + 3 * 3x * 4y(3x+4y)

17^3 =  27x^3 + 64y^3 + 36 xy * 17

4913 =  27x^3 + 64y^3 + 108*17

4913 =  27x^3 + 64y^3 +1836

27x^3 + 64y^3 = 4913 - 1836

27x^3 + 64y^3 = 3077

Answer 2

Answer:2077

Step-by-step explanation:

3x+4y=17.........(i)

xy=3..........(ii)

=> (3x+4y)^3=17^3....... (cubing both sides)

=> (3x)^3 +(4y)^3 +3*3x*4y(3x+4y)=(17)^3

=> 27x^3+64y^3+36*3*17= 4913...........(from i and ii)

=> 27x^3+64y^3+ 1836=4913

=> 27x^3+64y^3=4913-1836

=> 27x^3+64y^3=2077