1) 4X + 7X^2 = 0
X*( 4 + 7X) = 0
X1 = 0
7X = - 4
X2 = - 4/7
ответ 0 ; - 4/7
-----------------------
2) 13Х = 0,26X^2
13X - 0,26X^2 = 0
13X * ( 1 - 0,02X) = 0
13X = 0
X1 = 0
1 - 0,02X = 0
X2 = 50
Ответ 0 ; 50
------------------------
3) 64X^2 - 169 = 0
( 8X - 13) * ( 8X + 13) = 0
8X - 13 = 0
X2 = 1,625
8X + 13 = 0
X2 = - 1,625
Ответ 1,625 ; - 1,625
-----------------------------
4) 9X^2 + 28^2 = 197^2
9X^2 = 197^2 - 28^2 = ( 197 - 28)*( 197 + 28) = 169 * 225
V ( 9X^2) = V ( 169 * 225)
3X = 13 * 15
X = ( 13 * 15) / 3 = 13 * 5 = 45
Ответ 45 ; - 45