Let , , and be real numbers such that: , and . Let the sum of all possible values for , such that in any , , , and all satisfy the equations above, be . Determine the area of an equiangular triangle with side length . Round your answer to decimal places. A scientific calculator is allowed.
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Solve the triple-system of equations. By simplification, x + 2 y = z + 1 , x + 2 y = − z − 1 , 2 x − z = 4 y + 2 8 , and 4 x 2 − 5 y + 7 z = 1 7 0 0 . The 2 possible expressions for x and z resulted in the fact that an equation with an absolute value in both sides will split into 2 equations (the 1 st and 2 nd equation, shown above). The third equation resulted in from the equation 2 2 x − z = 1 6 y + 7 , where 2 x − z = 4 ( y + 7 ) = 4 y + 2 8 . I multiplied by 4 because of the fact that 1 6 = 2 4 . The 4 th equation (the quadratic) is given in the problem.
A good variable to solve for, in my opinion (you could solve for any) is y : In terms of y , x = 2 7 + 6 y (where z = 8 y + 2 6 ), and x = 3 2 y + 9 (where z = − 1 0 − 3 8 y ).
You should get 4 possible values for ( x + y + z ) : − 2 3 . 4 8 4 , 3 5 . 1 7 2 , 3 5 . 1 6 5 , and − 2 5 . 4 9 5 . Then, Sum all of the values to get 2 1 . 3 5 8 . Since the area of an equiangular, or equilateral triangle is ( s 2 ∗ 0 . 2 5 3 ) , where s = k = 2 1 . 3 5 8 , the area is 1 9 7 . 5 2 units 2 .