Answer:

Step-by-step explanation:
We are given that the equation of lines


According to question
The vector perpendicular to the lines is given by
and 
Therefore, the angle between two vectors is given by

Using the formula




Hence, the acute angle between the lines is given by

Answer: B
Step-by-step explanation:
We can rearrange the equation to get
, which clearly has complex roots.
It's unclear whether the ODE is

or

If the first case, then divide through both sides by
to get

then substitute
, so that
. Then




If the second, then dividing through by
gives

The same substitution as before gives




Answer:
Q
Step-by-step explanation:
3.990 because the 3 is less than 5 so the number stays the same.