Question

The centroid of the triangle formed by the points $(1,a),(2,b)$ and $(c^2,-3)$ lies on the x-axis, then

• A. $a+b=6$
• B. $a-b=6$
• C. $a+b=3$
• D. $a-b=3$

Answer 1

Answer: (C)

$a+b=3$

Point of $“D”\Rightarrow (1,a),(2,b),(c^2,-3)$

The center d lies at $(x,0)$

$\therefore \frac{1+2+c^2}{3}=x$

and $\frac{a+b-3}{3}=0$

$\therefore a+b=3$ option $C$ is correct.