To solve the quadratic equation given by 0=x^2-9x-20, we use the quadratic formula given by:
x=[-b+\- sqrt(b^2-4ac)]/(2a)
where,
a=1,b=-9,c=-20
thus substituting the above values into our formula we get:
x=[9+\-sqrt(9^2-4(-20*1))/(2*1)
x=[9+\-sqrt(161)]/2
x=[9+sqrt161]/2 or x=[9-sqrt161]/2
For the answer to the question above, we'll have to use the formula for velocity which is v =<u> d
</u> t and d = vt
Since the total distance is given, therefore we can get the time and it will look like this.
220t + 250t = 1880
<u>470t</u> = <u>1880
</u>470 470
the problem indicates that the train runs 250kph
Let's substitute:
d = 250(4)
the distance traveled by Lian is 1000km
<u>
</u>
we know that
The y-intercept is the value of the variable y when the variable x is equal to zero
therefore
the answer is the point 
