5х + 6у = -7 | *4
-4х - 5у = 2 | *5
20х + 24у = -28
-20х - 25у = 10
20х + 24у -20х - 25у = -28 + 10
-у = -18
<u>у = 18</u>
5х + 6у = -7
5х + 18*6 = -7
5х = -115
<u>х = -23
</u>х + у = 18 + (-23) = -5
или
5х + 6у = -7
-4х - 5у = 2
складываем оба уравнения
5х + 6у - 4х -5у = -7 + 2
х + у = 5
17/5=17:5=3целых 2/5
==========================
{4x-5y=-1
{x-5y=-4
x=5y-4
4(5y-4)-5y=-1
20y-16-5y=-1
15y=15
y=1
x=1
(1;1)
{2x-5y=-7
{x-3y=-5
x=3y-5
2(3y-5)-5y=-7
6y-10-5y=-7
y=3
x=4
(4;3)
Y ' - y*ctgx = 0
y' = dy/dx ==>
dy/dx = y*ctgx
dy/y = ctgx*dx
∫ dy/y = <span>∫ ctgx*dx
</span>ln y = ln (sinx)
y = sinx + C