Сумма длин всех рёбер прямоугольного параллелепипеда равна 112 см, два его измерения - 14 см и 9 см. найдите третье измерение параллелепипеда.

4х+4*14+4*9=112 4х+56+36=112 4х=112-56-36 4х=20 х=20÷4 х=5(см) третье ребро

Итак,  nowdays we can notice that gadgets got into all spheres of our life. i can't imagine my life without a smartphone or a tablet. we must agree that they take plenty of our free time, but they have much more benefits than negative point. i'd really like to have the new iphone but not due to the mainstream. i understand all the power and functions that can make my life easier and improve my work result and iphone can make his task better that other devises.  a mix of power and design made iphone a dream not obly for teenagers, but for businessmen and geeks. there ae lots of apps and games that can anser everything anywhere and games won't make me feel boring no matter what the situation is.  so, we can name (and people have already named) it as a real masterpiece that also can make calls.

решение:

x-5y=23                   x=23+5y           x=23+5y

7x+30y=-99           7x+30y=-99       7*(23+5y)+30y=-99

                                                        161+35y+30y=-99

                                                          65y=-161-99

                                                          65y= -260

                                                            y=-4

x=23+5*(-4)

x=3

ответ: (3,-4)