The sum of 2 consecutive whole numbers is frac ... - WAEC Mathematics 2010 Question
The sum of 2 consecutive whole numbers is \(\frac{5}{6}\) of their product, find the numbers
A
3, 4
B
1, 2
C
2, 3
D
0, 1
correct option: c
Let the no. be x and x + 1
x + (x + 1) = \(\frac{5}{6}\) of x(x + 1)
2x + 1 = \(\frac{5}{6}\) x(x + 1)
6(2x + 1) = 5x2 + 5x
12x + 6 = 5x2 + 5x
5x2 + 5x - 12x - 6 = 0
5x2 - 7x - 6 = 0
5x2 - 10x + 3x - 6 = 0
5x(x - 2) + 3(x - 2) = 0
(5x + 3)(x - 2) = 0
(5x + 3)(x - 2) = 0
(5x + 3) = 0
x - 2 = 0
for (5x + 3) = 0
5x = -3
x = \(\frac{-3}{5}\) (Imposible since x is a whole number)
x - 2 = 0
x = 2
x = \(\frac{-3}{5}\)(Impossible since x is a whole number)
x - 2 = 0
x = 2
The numbers are x = 2
x + 1 = 2 + 1
= 3
x + (x + 1) = \(\frac{5}{6}\) of x(x + 1)
2x + 1 = \(\frac{5}{6}\) x(x + 1)
6(2x + 1) = 5x2 + 5x
12x + 6 = 5x2 + 5x
5x2 + 5x - 12x - 6 = 0
5x2 - 7x - 6 = 0
5x2 - 10x + 3x - 6 = 0
5x(x - 2) + 3(x - 2) = 0
(5x + 3)(x - 2) = 0
(5x + 3)(x - 2) = 0
(5x + 3) = 0
x - 2 = 0
for (5x + 3) = 0
5x = -3
x = \(\frac{-3}{5}\) (Imposible since x is a whole number)
x - 2 = 0
x = 2
x = \(\frac{-3}{5}\)(Impossible since x is a whole number)
x - 2 = 0
x = 2
The numbers are x = 2
x + 1 = 2 + 1
= 3
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