Solve: 2x^2+7x-=9(mod19)

Answer 1

This is what we start with:

2x² + 7x = 9 (mod 19)

The expression "9 (mod 19)" means 9 modulo 19. Modulo is an arithmetic operation that returns the remainder of the division of one number by another. In this case, 9 divided by 19 gives a quotient of 0 with a remainder of 9, so 9 (mod 19) is 9.

2x² + 7x = 9

Then put it in the form to be able to be plugged into the quadratic formula or be factored.

2x² + 7x - 9 = 0

(x-1)(2x+9) = 0

So we have x-1 = 0 or 2x+9 = 0,

x = 1 or -4.5