Find the value(s) of a for which f(x) = 
– ax is an increasing function on R ?
We have,
f(x) = 
– ax
Given that f(x) is on increasing function
for all x 
R
⇒ 
for all x 
R
⇒ a < 
for all x 
R
But the last value of 3x2 = 0 for x = 0
∴a ≤ 0
35
Find the value(s) of a for which f(x) = – ax is an increasing function on R ?
We have,
f(x) = – ax
Given that f(x) is on increasing function
for all x R
⇒ for all x R
⇒ a < for all x R
But the last value of 3x2 = 0 for x = 0
∴a ≤ 0