S3 inequalities math question0

1. x is an integer satisfying the inequality in (a) and the inequality
-3x<or=21, write down all possible values of x.

So, where is inequality in (a)

2. If x>or=1, find the range of values of y in the following cases.
a). y=-0.5x
x>=1
0.5x>=0.5
-0.5x<=-0.5
y<=-0.5
b). y=7x-1/-3
x>=1
7x>=7
7x-1>=6
(7x-1)/3>=2
(7x-1)/(-3)<=-2
y<=-2

3. Given that x is a non-negative number smaller than 4.5
(a) Use an inequality to represent the value of x.
0<= x<4.5
(b) Furthermore if 5<or=y<or=6, use an inequality to represent the range of
x+1/y.
for 5<=y<=6, then 1/5>=y>=1/6
min value of x+1/y : x=0 and y=1/6, 0+1/6=1/6
max value of x+1/6: x=4.5 and y=1/5, 4.5+1/5=45/10+2/10=47/10
so, the range of x+1/y will be
1/6<=x+1/y < 47/10

4. x is a number not greater than5.
(a) Use an inequality to represent x.
x<5
(b) y is a number which is not greater than-5, Find the maximum value of x+y.
y<-5

x+y<5+(-5)
x+y<0