21 If 
( )
( )
( )
f x
g x
h x
y
l
m
n
a
b
c
=
, prove that 
( )
( )
( )
f
x
g x
h x
dy
l
m
n
dx
a
b
c
′
′
′
=
22 If y = 
acos1
x
e
−
, – 1 ≤ x ≤ 1, show that (
)
2
2
2
2
1
0
d y
dy
x
x
a y
dx
dx
−
−
−
= Rationalised 2023-24
 MATHEMATICS
146
Summary
® A real valued function is continuous at a point in its domain if the limit of the
function at that point equals the value of the function at that point