Question

22nd one quick with proper steps. One who will give correct answer will gain 30 points in no time but need proper steps...QUICK...

Answer 1

Hi friend !
As we know x³+y³=(x+y)(x²+y²-xy)
also x+y=5
SBS 
      (x+y)²= 25 
x²+y²+2xy= 25
  111+2xy= 25( x²+y²=111 (given ))
          2xy= 25-111
          2xy=-86
            xy= -43 ________(1) 
also x³+y³= (x+y)(x²+y²-xy)
                = (5)[111-(-43)]
                = 5 X [111+43]
                = 5 X 154
                = 770 
So, the option a)770 is correct  ......
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Answer 2

x + y = 5

(x + y)² = x² + y² + 2xy
5² = 111 + 2xy
25 = 111 + 2xy
2xy = - 86
xy = -43
- xy = 43

Now x³ + y³ = (x + y)( x² - xy + y²)
x³ + y³ = 5 ( 111 + 43)
x³ + y³ = 5 x 154
x³ + y³ = 770

Your answer is A

Hope This Helps You!