<span><span><span><span>x^2</span>+<span>8x</span></span>+15</span>=0</span>
Коэффициенты уравнения:
<span>a=1</span>, <span>b=8</span>, <span>c=15</span>
Вычислим дискриминант:
<span><span>D=<span><span>b2</span>−<span><span>4a</span>c</span></span></span>=</span><span><span><span><span>82</span>−<span><span>4·1</span>·15</span></span>=<span>64−60</span></span>=4</span>
<span><span><span><span><span>x1</span>=<span><span><span>−b</span>+D</span><span>/2a</span></span></span>=<span><span><span>−8</span>+2</span><span>/2·1</span></span></span>=<span><span>−6</span>/2</span></span>=<span>−3</span></span><span><span><span><span><span>
x2</span>=<span><span><span>−b</span>−D</span><span>/2a</span></span></span>=<span><span><span>−8</span>−2/</span><span>2·1</span></span></span>=<span><span>−10</span>/2</span></span>=<span>−5
</span></span><span><span><span><span><span>x^2</span>+<span>8x</span></span>+15</span>=<span><span>(<span>x+3</span>)</span><span>(<span>x+5</span>)</span></span></span>=<span>0</span></span>
(x+1-x+1)/(x-1)(x+1) >0
2/(x-1)(x+1) >0
x≠1 x≠-1
(-oo;-1)U(1;+oo)
А) -z-3z=4
-4z=4
z = -1
b) y-4y = 1
-3y = 1
y = -1/3
5x-5+3x-4x = 4x-5
2a-15-a+6 = a - 9
1.5a+a+2.5a = 5a
6y +8 +6y = 12y+8