Question

The perimeter of a triangle is 15x^2-23x+9 and two of its sides are 5x^2 8x-1 and 6x^2-9x+4.Find third place.

Answer 1

we know that sum of sides = perimeter
so...
$15 {x}^{2} - 23x + 9 = (5 {x}^{2} + 8x - 1) + (6 {x}^{2} - 9x + 4) + third \: side \\ 15 {x}^{2} - 23x + 9 = 11 {x}^{2} - x + 3 + third \: side \\ 4 {x}^{2} - 22x + 6 = third \: side$
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