(4х+3)(5-х)-х2=8х+19 Помогите)

Question

(4х+3)(5-х)-х2=8х+19 Помогите)

Answer 1

20х + 15 - 4х^2 -3x - x^2= 8x + 19
20x + 15 - 4x^2 - 3x - x^2 - 8x - 19 = 0
-5x^2 + 9x - 4 = 0
 5x^2 - 9x + 4 = 0
D = 81 - 4(5)(4) = 81 - 80 = 1;  Y = 1
x1 = (9 +1) / 10 = 1
x2 = (9 - 1) /10 = 0,8
Ответ: х1 = 1
           х2 = 0,8

Answer 2

20X - 4X^2 + 15 - 3X - X^2 = 8X + 19 
- 5X^2 + 17X + 15 - 8X - 19 = 0 
- 5X^2 + 9X - 4 = 0 
D = 81 - 80 = 1 ; √ D = 1 
X1 = ( - 9 + 1 ) : ( - 10) = 0,8 
X2 = ( - 10 ) : ( - 10 ) = 1