3-3(x+2)=5-4x
3-3х+6=5-4х
-3х+4х=5-3-6
Х=-8
Ответ: Х=-8
n² + x + 0.04 = n² + x + 0.2² = n² + 2*n*0.2 + 0.2² = n² + <u>0.4n</u> + 0.4 = (n+0.2)²
n² + x + 0.04 = n² + x + 0.2² = n² + 2*n*(-0.2) + 0.2² = n² - <u>0.4n</u> + 0.4 = (n-0.2)²
Ответ D
2а+b+2a²+ab = 2а+2a²+b+ab = 2a(1+a)+b(1+a) = (1+a)(2a+b)
(a + 1)x² <span>- (3a - 5)x + 1 = 0 имеет один корень при D = 0.
D = (3a - 5)</span>² - 4(a + 1) = 9a² - 30a + 25 - 4a - 4 = 9a² - 34a + 21;
9a² - 34a + 21 = 0,
D = 1156 - 4*21*9 = 400,
a = (34 <span>± 20)/18,
a_1 = 3,
a_2 = 7/9.
Ответ: 3; 7/9.</span>
Решение
<span>Cos 5п/9 cos 13п/9 - sin 5п/9 sin 13п/9= cos(5</span>π/9 + 13π/9) =
cos(18π/9) = cos2π = 1