<span>
</span>
<span>
x+3y=-12
</span>
y=-x/3-4
4x-6y=-12
4x-6*(-x/3-4)=-12
4x+2x+24+12=0
6x+24+12=0
6x+36=0
x=-36/6
x=-6
x+3y=-12
(-6)+3y=-12
6+3y=0
y=-6/3
y=-2
Ответ: x=-6; y=-2.
4^x=m
5^y=n
m n >0
mn=8
m-n=11
m=11+n
n(n+11)=8
n²+11n-8=0
D=121+32=153
n12=(-11+-√153)/2
n=(-11+√153)/2
m= 11+(-11+√153)/2
x=log5(11+(-11+√153)/2)
y=log4((-11+√153)/2)
1/7х-15=1/4х+3 1/7 -1/4= 4/28 - 7/28= - (7/28-4/28)= - 3/28=
1/7х-1/4х=15+3 18:(-3/28)= - 18*28
- 3/28х=18 ------- = 168
х= 18 : (-3/28) 3
х=168
1200 тенге + 4% или 1200 * 1,04= 1248 тенге