3
y(8)=√(8-4)=2
y`=1/(2√(x-4))
y`(8)=1/(2*2)=1/4
y=2+1/4*(x-8)=2+1/4*x-2=1/4*x
4
D=(-8/2)^2-15=16-15=1
x1=((-b/2)+VD)/a=(4+1)/1=5
x2=((-b/2)-VD)/a=(4-1)/1=3
Ответ:3;5.
5х*(х+3) 5х*(х+3)
---------------- = -------------- = 5
х²+3х х(х+3)
X/(x³+1)-1/(x²-x+1)=1/7
x/[(x+1)*(x²-x+1)]-1/(x²-x+1)=1/7
[x-(x+1)]/[(x+1)*(x²-x+1)]=1/7
-1/[(x+1)*(x²-x+1)]=1/7. пропорция
-7=(x+1)*(x²-x+1), x³+1=-7, x³+8=0
x³=-8, x=-2
<u>ответ: x=-2</u>