Answer:
[tex]85\:\mathrm{units^2}[/tex]
Step-by-step explanation:
All side lengths of a square are equal. The three squares create a right triangle, and the hypotenuse of this triangle represents the side length of the square.
All right triangles must follow the Pythagorean Theorem [tex]a^2+b^2=c^2[/tex] where [tex]c[/tex] is the hypotenuse of the triangle.
Therefore, let [tex]h[/tex] be the side length of this largest square. Since the area of a square with side length [tex]s[/tex] is given by [tex]s^2[/tex], [tex]h^2[/tex] will represent the area of the square:
[tex]\sqrt{35}^2+\sqrt{50}^2=h^2=\boxed{85\:\mathrm{units^2}}[/tex]