The sum of the first n positive integers is
...The sum of the first n positive integers is
1/2 n(n-1)
n(n+1)
n(n-1)
1/2 n(n+1)
Correct answer is D
Let the positive integers be 1, 2, ,3, 4, .....n
∴ a = 1, d = 1 and n = n
Sn = n/2(2a + (n-1)d)
= n/2 (2 + n – 1)
= 1/2n(n + 1)
Solve the simultaneous equations for x in x2 + y - 8 = 0, y + 5x - 2 = 0...
If \(p\propto \frac{1}{q}\), which of the following is true?...
Evaluate: \(\frac{0.42 \div 2.5}{0.5 \times 2.95}\), leaving the answer in the standard form....
In ∆PQR. ∠PQR is a right angle. |QR| = 2cm and ∠PRQ = 60o. Find |PR|...
Evaluate \(\int\limits_0^\frac{\pi}{2}\) sin xdx...
If K is a constant, which of the following equations best describes the parabola? ...