可否解答一些中四數學題目(20分)

(1) 5x>2(x^2+1)
=>-2x^2+5x+8-10>0
=>y>10
So the no. integral solution is 1
(2)
Volume of I : Volume of (I+II) : Volume of (I+II+III)
=1:8:27
=> Volume of II:Volume of III=7/19
(3)
The answer is C because the system of equations is just equal to x^2-bx+c=0 which have two real solutions.
(4)
Given y=3x^2+x-8. Want to solve 3x^2-x-5=0
y=3x^2+x-8=(3x^2-x-5)+(2x-3)
If I set 3x^2-x-5=0, then y=2x-3
So the answer is B