Объяснение:
x+x-y = 23
2x-y = 23
<u><em>y = 2x-23</em></u>
<u />
x+y+y = 54
x+2y = 54
<u><em>2y = 54-x</em></u>
<u />
y-z-z = 7
y-2z = 7
<u><em>y = 7+2z</em></u>
<u><em /></u>
2x-23 = 7+2z
2x = 7+2z+23
2x = 2z+30
x = (2z+30):2
<u><em>x = z+15</em></u>
<u><em /></u>
2y = 54-x
2y = 54-(z+15)
2y = 54 - z - 15
2y = 39-z
<u><em>y = (39-z):2</em></u>
<u><em /></u>
y = y
(39-z):2 = 7+2z
39-z = 2(7+2z)
39-z = 14+4z
-z-4z = 14 - 39
-5z = -25
<u><em>z = 5</em></u>
<u><em>y = 7+2z = 7+2*5 = 17</em></u>
<u><em>x = z+15 = 5+15 = 20</em></u>
y+x*z-z = 17+20*5-5 = 17+100-5 = <u>112</u>
<u />
<h3>Ответ: 112.</h3>
Y-4y=1 -3y=1 y=-1\3 7x+3x=-5 10x=-5 x=-0.5
X*2 + y*2 = 58
x*2 + 2xy + y*2 - 2xy = 58
(x + y) *2 = 58 + 2xy
(x+y)*2 = 58 + 42
(x+y)*2 = 100
x+y = 10
x = 10 - y
Подставляем
(10-y) y = 21
y*2 - 10y + 21 = 0
y*2 - 10y + 25 - 25 + 21=0
(y-5)*2 = 4
y-5=2
y=7
x=10-7=3
* - это степень
Х первое равно 0
х второе равно 3