X^2 + x < 72
x^2 +x - 72< 0
D = 1 + 4*72 = 1 + 288 = 289 = 17^2
x1 = ( - 1 + 17)/2 = 16/2 = 8 ;
x2 = ( - 1 - 17)/2 = - 18/2 = - 9;
(x + 9) ( x - 8) < 0
+ - +
------------- ( - 9) ------------- ( 8 ) ------------> x
x ∈ ( - 9; 8)
Целые решения:
<u>- 8 ; - 7; - 6; - 5; - 4; </u>- <u>3; - 2; - 1; 0 ; 1 </u>; <u>2 ; 3; 4 ; 5 ; 6</u> ; 7
Ответ: 16
<span>-3а^2-6ав-3в^2=</span>=(1,5а-1,5в)^2
(x² + 3x) /8 - x / 2 = 0
(x² + 3x) /8 = x / 2
8x = 2( x² + 3x)
8x = 2x² + 6x
8x - 2x² - 6x = 0
- 2x² + 2x = 0
2x² - 2x = 0
D = b² - 4ac = (-2)² - 4 × 2 × 0 = 4 = 2²
x₁ = 2 + 2 / 4 = 4/4 = 1
x₂ = 2 - 2 / 4 = 0 / 4 = 0