ОДЗx²+1>0 при любом х7x²-3x+1)>0 при любом х,т.к.D<0x∈(-∞;∞)lg(x²+1)log(7x²-3x+1)+lg(x²+1)log(7x²-3x+1)≤02lg(x²+1)log(7x²-3x+1)≤01)lg(x²+1)≤0⇒x²+1≤1⇒x²≤0⇒x=0lg(7x²-3x+1)≥0⇒7x²-3x+1≥1⇒7x²-3x≥0⇒x(7x-3)≥0⇒x≤0 U x≥3/7x=02)lg(x²+1)≥0⇒x²+1≥1⇒x²≥0⇒x-любоеlg(7x²-3x+1)≤0⇒7x²-3x+1≤1⇒7x²-3x≤0⇒x(7x-3)≤0⇒0≤х≤3/7x∈[0;3/7]