Hey, how did you factored
2a2−3a−2=0?
Set equation equal to zero:
2a2−3a−2=0Factor:
(a−2)(2a+1)=0GreenlightTestPrep wrote:
Carcass wrote:
The points (a+1, 1), (2a+1, 3) and (2a + 2, 2a) lie on the same straight line if
(A) a = -1 or 2
(B) a = 2 or 1
(C) a = 2 or −1/2
(D) a = 2 or 1/2
(E) None of these.
Key property: If the three points are on the same straight line, then the slope between any two points will always be the SAMEIn other words:
The slope between (a+1, 1) and (2a+1, 3) = the slope between (2a+1, 3) and (2a + 2, 2a)So, we can apply the slope formula to write:
3−1(2a+1)−(a+1)=2a−3(2a+2)−(2a+1)Simplify to get:
2a=2a−31Cross multiply to get:
(a)(2a−3)=(2)(1)Simplify:
2a2−3a=2Set equation equal to zero:
2a2−3a−2=0Factor:
(a−2)(2a+1)=0So,
a=2 or
a=−12Answer: C