-15 and -42 both add to -57 and multiply to 630
Answer
Find out the what is the best estimate of the number of liters Ajay's car used .
To prove
As given
Ajay's car used 314 gallons of gas on a trip to the beach.
Assume 1 gallon = 3.8 liters
Than
The number of liters Ajay's car used = 314 × 3.8
= 1193.2 litres
Therefore 1193.2 litres Ajay's car used .
which follows from the usual change of coordinates via
and Jacobian determinant
Swap the order, so that the integral is
and now let
, so that
. Now, you have