Answer:
{-4, 5/4}
Step-by-step explanation:
Note: most Brainly users don't have access to Quadra 1, so you may as well omit that when you post a question.
By "4x2 +1 1x - 20=0" I assume you meant 4x^2 +11x - 20=0 (11, not 1 1, and use " ^ " to denote exponentiation, please).
Here I will use the quadratic formula. Here, a = 4, b = 11 and c = -20, so the discriminant is
b²-4ac = 121 - 4(4)(-20), or 121 + 320, or 441.
Since this is positive, the quadratic has two unequal, real roots.
- 11 ± √441
The roots are x = ------------------
2(4)
-11 ± 21
or x = ------------ → x = 10/8 or x = 5/4; also x = -32/8 or x = -4.
8
The roots are {-4, 5/4}
