<span>7x-5/x-1=2
</span>7x-5/x-2-1=0
7x-5/x-3=0
сводим к общему знаменателю х
7х2/х-5/х-3х/х=0
7х2 - 3х - 5=0
Коэффициенты уравнения:
<span>a=7</span><span>, </span><span>b=<span>−3</span></span><span>, </span><span>c=<span>−5</span></span>
<span>Вычислим дискриминант: </span>
<span><span>D=<span><span>b2</span>−<span><span>4a</span>c</span></span></span>=</span><span><span><span><span><span>(<span>−3</span>)</span>2</span>−<span><span>4·7</span>·<span>(<span>−5</span>)</span></span></span>=<span>9+140</span></span>=149</span>
<span>(<span>D>0</span>)</span>, следовательно это квадратное уравнение имеет 2 различных вещественных корня:
Вычислим корни:
<span><span>x<span>(<span>1,2</span>)</span></span>=<span><span><span>−b</span>±<span>√D</span></span><span>2a
</span></span></span><span><span><span><span><span><span>x1</span>=<span><span><span>−b</span>+<span>√D</span></span><span>2a</span></span></span>=<span><span><span><span>−<span>(<span>−3</span>)</span></span>+12</span>,207</span><span>2·7</span></span></span>=<span><span>15,207</span>14</span></span>=1</span>,086
</span><span><span><span><span><span><span>x2</span>=<span><span><span>−b</span>−<span>√D</span></span><span>2a</span></span></span>=<span><span><span><span>−<span>(<span>−3</span>)</span></span>−12</span>,207</span><span>2·7</span></span></span>=<span><span><span>−9</span>,207</span>14</span></span>=<span>−0</span></span>,658</span>
<span><span><span><span><span>7<span>x2</span></span>−<span>3x</span></span>−5</span>=<span><span>(<span><span>x−1</span>,086</span>)</span><span>(<span><span>x+0</span>,658</span>)</span></span></span>=0
</span>Ответ:
<span><span><span>x1</span>=1</span>,086</span>
<span><span><span>x2</span>=<span>−0</span></span>,<span>658
</span></span>
<span>найти число(-13x+2)в квадрате +x
</span>
(-13*1,086+2)в квадрате +1,086=147,93
(-13*(-0,658)+2)в квадрате -0,658=292,02
2 целых 5/8 +1 целая 3/10 =2,625+1,3=3,925
6 целых 7/10 - 4 целых 5/12 = 6 целых 42/60 - 4 целых 25/60 = 2 целых 17/60
V=3.14*12*12*9=4069.44см кубических
85процентов будет:4069.44*0.85=3459.02см кубических
