1) (4x-3)²/(7x²+3) ≥x²/(7x²+3)
(4x-3)²/ (7x²+3) - x²/(7x²+3) ≥0
(15x²-24x+9)(7x²+3)≥0
x=1; x=3/5;
otvet:x∈(-∞;3/5]∪[1; +∞)
3)4/(x²-4x)≤1/(x-4)
4/(x(x-4)) - 1/(x-4)
(4-x)/(x(x-4))
(4-x)(x(x-4))≤0
x≥4; x≤0; x≤4
otvet: x∈[0;4]∪[4;+∞)
2) (3x-2)/ (4x²+9) ≤ (3x-2)/(4x²+5)
(3x-2)[4x²+5- 4x²-9]/ (4x²+9)(4x²+5)
(8-12x)(4x²+9)(4x²+5)≤0
x≥2/3;
otvet:x∈[2/3;+∞)