To find the x intercept set y = 0
x^2 + x - 2 =0
(x+2)(x-1) = 0
x = -2 , x = 1
Answer:
There is no short answer.
Step-by-step explanation:
To find to intervals which f(x) increases or decreases, we first need to find it's derivative.

The function is increasing when it's value is > 0 and decreasing when it's value is < 0.
If we take a look at this graph, cosx+sinx is positive when they are both positive or when cosx is greater then sinx on the negative part.
I hope this answer helps.