A1)
![\left \{ {{2x\ \textless \ 15} \atop {3x+1\ \textgreater \ 7}} \right. \left \{ {{x\ \textless \ \frac{15}{2} } \atop {3x\ \textgreater \ 7-1}} \right. \left \{ {{x\ \textless \ 7,5} \atop {3x\ \textgreater \ 6}} \right. \left \{ {{x\ \textless \ 7,5} \atop {x\ \textgreater \ 2}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7B2x%5C+%5Ctextless+%5C+15%7D+%5Catop+%7B3x%2B1%5C+%5Ctextgreater+%5C+7%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C++%5Cfrac%7B15%7D%7B2%7D+%7D+%5Catop+%7B3x%5C+%5Ctextgreater+%5C+7-1%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C+7%2C5%7D+%5Catop+%7B3x%5C+%5Ctextgreater+%5C+6%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C+7%2C5%7D+%5Catop+%7Bx%5C+%5Ctextgreater+%5C+2%7D%7D+%5Cright.+)
2<x<7,5
Ответ: 3)5
А2)
![\left \{ {{ \frac{1}{3}x\ \textgreater \ 1} \atop {-8x\ \textgreater \ -16}} \right. \left \{ {{x\ \textgreater \ 1: \frac{1}{3} } \atop {8x\ \textless \ 16}} \right. \left \{ {{x\ \textgreater \ 3} \atop {x\ \textless \ 2}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7B+%5Cfrac%7B1%7D%7B3%7Dx%5C+%5Ctextgreater+%5C+1%7D+%5Catop+%7B-8x%5C+%5Ctextgreater+%5C+-16%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextgreater+%5C+1%3A+%5Cfrac%7B1%7D%7B3%7D+%7D+%5Catop+%7B8x%5C+%5Ctextless+%5C+16%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextgreater+%5C+3%7D+%5Catop+%7Bx%5C+%5Ctextless+%5C+2%7D%7D+%5Cright.+)
x∈∅
Ответ: 4)∅
А3)
![\left \{ {{1,5x+0,5\ \textgreater \ 2} \atop {0,7x-0,2\ \textless \ 4}} \right. \left \{ {1,5x\ \textgreater \ 1,5} \atop {0,7x\ \textless \ 4,2}} \right. \left \{ {{x\ \textgreater \ 1} \atop {x\ \textless \ 6}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7B1%2C5x%2B0%2C5%5C+%5Ctextgreater+%5C+2%7D+%5Catop+%7B0%2C7x-0%2C2%5C+%5Ctextless+%5C+4%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B1%2C5x%5C+%5Ctextgreater+%5C+1%2C5%7D+%5Catop+%7B0%2C7x%5C+%5Ctextless+%5C+4%2C2%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextgreater+%5C+1%7D+%5Catop+%7Bx%5C+%5Ctextless+%5C+6%7D%7D+%5Cright.+)
x∈(1;6)
Целочисленные решения: 2, 3, 4, 5
Ответ: 2)4
А4)
![\left \{ { \left \{ {{3x\ \textgreater \ 7} \atop {6x\ \textless \ 20}} \right. \atop {5x\ \textgreater \ 15}} \right. \left \{ {{ \left \{ x\ \textgreater \ 7/3 \atop {x\ \textless \ 10/3}} \right. } \atop {x\ \textgreater \ 3}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B+%5Cleft+%5C%7B+%7B%7B3x%5C+%5Ctextgreater+%5C+7%7D+%5Catop+%7B6x%5C+%5Ctextless+%5C+20%7D%7D+%5Cright.++%5Catop+%7B5x%5C+%5Ctextgreater+%5C+15%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7B+%5Cleft+%5C%7B+x%5C+%5Ctextgreater+%5C+7%2F3+%5Catop+%7Bx%5C+%5Ctextless+%5C+10%2F3%7D%7D+%5Cright.+%7D+%5Catop+%7Bx%5C+%5Ctextgreater+%5C+3%7D%7D+%5Cright.+)
x∈(3;10/3)
ОТвет: 1)(3;10/3)
В1)
![\left \{ {{-x+8\ \textgreater \ 0} \atop {6x+2\ \textgreater \ 0}} \right. \left \{ {{x\ \textless \ 8} \atop {6x\ \textgreater \ -2}} \right. \left \{ {{x\ \textless \ 8} \atop {x\ \textgreater \ - \frac{1}{3} }} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7B-x%2B8%5C+%5Ctextgreater+%5C+0%7D+%5Catop+%7B6x%2B2%5C+%5Ctextgreater+%5C+0%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C+8%7D+%5Catop+%7B6x%5C+%5Ctextgreater+%5C+-2%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C+8%7D+%5Catop+%7Bx%5C+%5Ctextgreater+%5C+-+%5Cfrac%7B1%7D%7B3%7D+%7D%7D+%5Cright.+)
Ответ: х∈(-1/3;8)
В2)
![\left \{ {{6x\ \textless \ 36} \atop {x\ \textgreater \ b}} \right. \left \{ {{x\ \textless \ 36/6} \atop {x\ \textgreater \ b}} \right. \left \{ {{x\ \textless \ 6} \atop {x\ \textgreater \ b}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7B6x%5C+%5Ctextless+%5C+36%7D+%5Catop+%7Bx%5C+%5Ctextgreater+%5C+b%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C+36%2F6%7D+%5Catop+%7Bx%5C+%5Ctextgreater+%5C+b%7D%7D+%5Cright.+%5Cleft+%5C%7B+%7B%7Bx%5C+%5Ctextless+%5C+6%7D+%5Catop+%7Bx%5C+%5Ctextgreater+%5C+b%7D%7D+%5Cright.++)
Ответ: при b=6, система не имеет решений
С1)основание равно 16
P - периметр (сумма всех сторон) =48
треугольник равнобедренные, значит боковые стороны равны друг другу, отсюда:
боковую сторону обозначим за х и составим уравнение:
48=16+2x
48-16=2x
32=2x
x=32/2=16
В итоге, как мы видим, треугольник равносторонний и ве его стороны равны 16 см
Если есть вопросы - задавай