Answer:

Step-by-step explanation:
For the quadratic equation
the discriminant is defined as

and the quadratic formula for the roots gives us two roots:

and

For the equation
use quadratic formula to find roots:

So,

Answer:
(x, y) = (2, -5)
Step-by-step explanation:
Subtract 3 times the first equation from the second:
(-2x +3y) -3(-7x +y) = (-19) -3(-19)
19x = 38 . . . simplify
x = 2 . . . . . . divide by 19
Substituting into the first equation, we have ...
-7(2) +y = -19
y = -5 . . . . . . . . add 14
The solution is (x, y) = (2, -5).
Be more specific! What is your question?
187-16= 171
171 / 9= 19
The books were $19 dollars each.