1) x²-13x+40=0
x1=8 x2=5
6x²+x-1=0
x1=( -1-√(1+24))/12=-1/2
x2=( -1+√(1+24))/12=1/3
2)
a²-18a+17=(a-17)(a-1)
-x²-4x+21=-(x+7)(x-3)
60y²-20y-5=5(12y²-4y-1)=5(y+1/6)(y-1/2)
y1=(2-√(4+12))/12=-1/6
y2=(2+4)/12=1/2
3)
(x²+3x-4)/(x+4)=(x+4)(x-1)/(x+4)=x+1
(3x-9)/(x²+4x-21)= 3(x-3)/[(x-3)((x+7)]= 3/(x+7)
(3x²-x-2)/(9x²-4)=3(x+2/3)(x-1)/[(3x+2)(3x-2)]=(x-1)/(3x-2)
3x²-x-2=0
x1=(1-√(1+24))/6=-2/3
x2=(1+√(1+24))/6=1
4) y=(x²-3x-10)/(x+2) область определения функции : x≠-2
y=(x+2)(x-5)/(x+2)
y=x-5 прямая, на которой выколота точка x=-2 y=-7
5)
[ (3y²-10y+8)/(4y²-36) ]·[(y-3)/(y-2)] +{(0,25y/(y+3)]=
[ 3(y-4/3)(y-2)/(4(y-3)(y+3)) ]·[(y-3)/(y-2)] +{y/(4(y+3))]=
[ 3(y-4/3)/(4(y+3)) ] +{y/(4(y+3))]=(3y-4+y)/4(y+3)=(y-1)/(y+3)