1. 9x^2-49x=0
x(9x-49)=0
x=0
x=49/9
2. 25x^2+36=0
25x^2=-36
нет решений
3. (3x+1)^2-100=0
(3x+1)^2=100
3x+1=10
3x=9
x=3
4. 7x^3-63x=0
7x(x^2-9)=0
x=0
x=-/+3
5.
49x^3-14x^2+x=0
x(49x^2-14x+1)=0
x=0
49x^2-14x+1=0
D=196-4*49=0
x=14/98=1/7
6.
x^3-5x-x+5=0
x^3-6x+5=0
(x-1)(x^2-x-5)=0
x=-/+√21/2-1/2
x=1