MHB What are the possible values of x and y in the equation x + 2y > 5?

[squexy]

View attachment 3780

1
x + 2y > 5
x +y> 2,5 (.-1)

x + 2y > 2,5
-x - y > -2,5

y > 2,5
x> 0

View attachment 3779Log 9 - log 4´= log 5

5 * log 5 =
2^5 * 0,6989
2^3,4948
11,27300

 

[evinda]

View attachment 3780

1
x + 2y > 5
x +y> 2,5 (.-1)

x + 2y > 2,5
-x - y > -2,5

y > 2,5
x> 0

How did you get the second inequality? (Thinking)

 

[squexy]

How did you get the second inequality? (Thinking)

My apologies, the post was confusing.

n= 5
x + 2y = n
x + 2y > 5
x +y> 2,5
-x - y > -2,5
y > 2,5 - xx+2y > 5
x + 2(2,5 -x) > 5
x>0

x+y>2,5
y > 2,5

 

[evinda]

My apologies, the post was confusing.

n= 5
x + 2y = n
x + 2y > 5
x +y> 2,5
-x - y > -2,5
y > 2,5 - xx+2y > 5
x + 2(2,5 -x) > 5
x>0

x+y>2,5
y > 2,5

How did you get to the inequality $x+y>2.5$ ?

 

[squexy]

How did you get to the inequality $x+y>2.5$ ?

I divided 5 by 2.
x + 2y > 5
x + y > 5/2
x + y > 2,5

 

[evinda]

I divided 5 by 2.
x + 2y > 5
x + y > 5/2
x + y > 2,5

If you want to divide by 2, the inequality will become $\frac{x+2y}{2} > \frac{5}{2} \Rightarrow \frac{x}{2}+y>2.5$.

 

[squexy]

If you want to divide by 2, the inequality will become $\frac{x+2y}{2} > \frac{5}{2} \Rightarrow \frac{x}{2}+y>2.5$.

So I should not divide by 2 otherwise I will get x=0, I must be wrong from the begging how could I start to solve the 1 question?

 

[evinda]

So I should not divide by 2 otherwise I will get x=0, I must be wrong from the begging how could I start to solve the 1 question?

We add $x$ to $2y$ in order to get $n$. So notice that both of them have to be $\leq n$. You also have to take into consideration the fact that we are looking for positive integers.