(√5)^(㏒₂3) / (√3)^(㏒₂5) = 5 ^((1/2)*㏒₂3) / 3^((1/2)*㏒₂5) =
= ㏒₂ 5 ^((1/2)*㏒₂3) / ㏒₂ 3^((1/2)*㏒₂5) = (1/2)*㏒₂ 3* ㏒₂ 5 / (1/2)*㏒₂5* ㏒₂ 3 =1
= х(3-у)-у(3-у)=(3-у)(х-у)
Arccos(x)`=-1/(√(1-x²)
arccos²(x)`=-2*arccos(x)/√(1-x²)
1/arccos²(x)=(1`*arccos²(x)-1*arccos²(x)`)/arccos⁴(x)=
=(0-(-2*arccos(x)/√(1-x²))/arccos⁴(x)=2*arccos(x)/(arccos⁴(x)*√(1-x²)).
X+3 3x-2
----- = ------ |:15
3 5
5x+15=9x-6
5x-9x=-15-6
-4x=-21
x=-21:-4
21
x=--------
4
Или;x=5,25