Answer:
A. 5
Explanation:
The triangle will be a right triangle when the side lengths satisfy the Pythagorean theorem: the sum of the squares of the legs is equal to the square of the hypotenuse.
(x +1)^2 +x^2 = (√61)^2
x^2 +2x +1 +x^2 = 61 . . . eliminate parentheses
2x^2 +2x = 60 . . . . . . .subtract 1, collect terms
x^2 +x -30 = 0 . . . . . divide by 2, subtract 30
(x +6)(x -5) = 0 . . . . factor the quadratic
x = -6 or +5
The solution is x = 5.
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Side lengths cannot be negative. Solution values are values of x that make the factors zero. x+6=0 when x=-6, for example.