Пошаговое объяснение:

1) x⁴-13x²+36=0

a²-13a+36=0

a²-4a-9a+36=0

a(a-4)-9(a-4)=0

(a-4)(a-9)=0

a=4 a=9

x²=4 x²=9

x=±2 x=±3

2) x⁴-x²-12=0

b²-b-12=0

b²+3b-4b-12=0

b(b+3)-4(b+3)=0

(b+3)(b-4)=0

b=-3 b=4

x²=-3 x²=4

x€R x=±2

3) c²-4c-12=0

c²+2c-6c-12=0

c(c+2)-6(c+2)=0

(c+2)(c-6)=0

c=-2 c=6

x²-3=-2 x²-3=6

x=±1 x=±3

4) x/(x+5) + (x+5)/(x-5) - 50/(x²-25)=0

x/(x+5) + (x+5)/(x-5) - 50/ ( x-5)×(x+5)=0

x(x-5) + (x+5)²-50/ (x-5) (x+5)=0

(x+5)(x-10+x+5) / (x-5)(x+5) =0

2x-5/ x-5 =0

2x-5=0

2x=5

x= 2,5