1
1)(7-2x)/52(7-2x)<5x+10<br>14-4x-5x-10<0<br>9x>4
x>4/9
x∈(4/9;∞)
2)1/(3+8x-3x²)≥0
1>0⇒3+8x-3x²>0
3x²-8x-3<0<br>D=64+36=100
x1=(8-10)/6=-1/3
x2=(8+10)/6=3
x∈(-1/3;3)
Ответ x∈(-1/3;4/9) U (4/9;3) U (3;∞)
2
2x²+5x+p=0
D=25-8p>0⇒8p<25⇒p<3,125<br>x1+x2=-2,5 U x1*x2=-0,5p
x1²+3x1x2+x2²≤6
x1²+x2²=(x1+x2)²-2x1x2
(x1+x2)²-2x1x2+3x1x2≤6
(x1+x2)²+x1x2≤6
6,25-0,5p≤6
0,5p≥0,25
p≥0,5
p∈[0,5;3,125)