The equation of parabola is 
. If a is positive and 
is always greater than zero or equal to zero, then x is also greater or equal to zero. This means that parabola is determined for non-negative x and for all real y.
Tha canonical equation of parabola is 
, where p>0. The branches of this parabola go up in positive y-direction. When you change x to y and y to x, then the branches of parabola go in positive x-direction, that is right.
Answer: correct choice is A.
Answer:
sine 23 = x/21
Multiply both sides by 21
21 x sine 23 = x
Now, use a calculator and find the answer of the 21 times the sine of 23:
x = -17.7706284876
25 = 5*5 and 9 = 3*3, which we can exploit to write
so that this expression is actually a difference of squares. We can factorize this to get
and given that 
, we divide both sides by this to get
