Write the interval in which f(x) = sin x + cos x, xϵ[0, π/2] is increasing.
f(x) = Sin x + Cos x, x ϵ [0, 
]
f’(x) = Cos x – Sin x
For, f(x) to be increasing, it must have
f’(x) > 0
Cos x – Sin x > 0
Sin x < Cos x
tan x < 1
tan x < tan 
x ϵ 
Hence, the required interval is x ϵ 
.
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