3x^2 - 10x + 30 = 7x^2 + 2x + 3
- 4x^2 - 12x + 27 = 0
4x^2 + 12x - 27 = 0
D = 144 + 16*27 = 576 = 24^2
x1 = ( - 12 + 24)/8 = 1,5
x2 = ( - 12 - 24)/8 = - 4,5
1-x>0, 17-x-x^2>0;
-x>-1, x<1,
x^2+x-17<0,
x^2+x-17=0,
D=69,
x1=(-1-√69)/2≈-4,7; x2=(-1+√69)/2≈3,7;
(-1-√69)/2<x<(-1+√69)/2,
(-1-√69)/2<x<1,
x∈((-1-√69)/2;1);
log_3 (1-x) = log_3 (17-x-x^2),
1-x=17-x-x^2,
x^2-16=0,
(x+4)(x-4)=0,
x+4=0, x1=-4,
x-4=0, x2=4∉((-1-√69)/2;1),
x=-4.