1) 220/128 + 350/256 = 220/128 + 175/128 = 395/128 = 3 11/128
2) 300/15 + 691/4 = 20 + 170 + 11/4 = 192 3/4
3) 111/40 + 561/6 = 2 31/40 + 93 3/6 = 95 31/40 + 20/40 = 95 51/40 = 96 11/40
4) 35/38 + 83/81 = (35*81+38*83)/(38*81) = 5989/3078 = 1 2911/3078
1)15x²+8x+1=15(x+1/3)(x+1/5)
D=64-60=4
x1=(-8-2)/30=-1/3
x2=(-8+2)/30=-1/5)
20x²-31x+12=20(x-3/4)(x-4/5)
D=961-960=1
x1=(31-1)/40=3/4
x2=(31+1)/40=4/5
(15x²+8x+1)/(20x²-31x+12)≤0
+ _ + _ +
-------------[-1/3]-------[-1/5]-----(3/4)----------(4/5)----------
x∈[-1/3;-1/5] U 93/4;4/5)
2){2x-x>8-2⇒x>6
{x²-2x-63≥0⇒x≤-7 U x≥9
x1+x2=2 U x1*x2=-63⇒x1=-7 U x2=9
x∈[9;∞)
X^2+y^2+10x+6y+34=0
Решение: