Question

Help! show working out please!

Answer 1

Q2) \[z = x - y\]
x has to be the least number possible & y has to be the greatest number possible. That way, we get the lowest number.
x can be: 0 to 6 --> because it can not be less than 0 or more than 6.
y can be: 0 to 7 --> because it can not be less than 0 or more than 7.
The lowest number for x is 0
The highest number of y is 7.
\[z = 0 - 7\]
\[z = -7\]

Answer 2

ok got it, how about the other harder ones?

Answer 3

Q3)
There are two equations they give us.
Equation1: \[3x + 2y \le 18\]
Equation2: \[3x+4y = z\] ---> Equation2 can be also written as: \[3x + 2y = z - 2y\]
SO:
Equation1: \[3x + 2y \le 18\]
Equation2: \[3x + 2y = z - 2y\]

Basically, since the the left hand side of both equations is the same, it 'cancels out'.
Lets make the right hand side the maximum number, which is 18.
So it becomes...
\[18 = z-2y\]
To substitute y in this equation, we take the maximum value possible for y.
\[y \le 3\] With this equation given, we can tell that 3 is the maximum value possible for y. So substitute y = 3.
\[18 = z-2y\]
\[18 = z-6\]
\[18 + 6 = z\]
\[24 = z\]

Answer 4

wait, um where did the y≤3 come from?

Answer 5

y≤3 came from the information given in the question. :)

Answer 6

oh yeh it did, sorry i didn't see it lol, i'm 2 blind. Btw is there another way of doing it? like an easier method? and by any chance do u know if there is a more specific name for those type of questions?

Answer 7

I'm not so sure. That's the way I know how to do them, and with practise it gets easier. I think these questions come under inequalities. No specific name that I know of. :S

Answer 8

i think i found a site that helps me but thanks so much for your help. Btw there is an easier way to solve it like rearrange all the graphs to y= ...... and then plot it and shade the required or unrequired region depending on which one your teacher accepts or smth. yeh thanks once again!