Question

7y во второй степени + 5y -2=0

Answer 1

7y^2 + 5y - 2 = 0 
D = 25 + 4*7*2 = 25 + 56 = 81 = 9^2
y1 = ( - 5 + 9)/14 = 4/14 = 2/7;
y2 = ( - 5 - 9)/14 = - 14/14 = - 1;

Ответ:
- 1;  2/7