Step-by-step explanation:
x, x+1, x+2 are the 3 consecutive positive integers.
(x+1)(x+2) = 2(x+1) + 2×(x+x+1+x+2)
x² + 3x + 2 = 2x + 2 + 2×(3x + 3)
x² + 3x + 2 = 2x + 2 + 6x + 6 = 8x + 8
x² - 5x - 6 = 0
we can solve this by finding the factoring.
that means we find a, b so that
(x - a)(x - b) = x² - 5x - 6 = 0
because then x = a and x = b are the 2 solutions of the quadratic equation.
we have
x² - ax - bx + ab = x² - (a+b)x + ab = x² - 5x - 6
a+b = 5
ab = -6
that means, either a or b must be 6 and the other -1.
so we get
(x - 6)(x + 1) = 0
x = 6
or
x = -1
since we are only looking for positive integers, the x = -1 solution is invalid, and we get only x = 6 as solution.
therefore the 3 consecutive positive integers are
6, 7, 8
