Sum/difference:
Let
This means that
Now, assume that 
is rational. The sum/difference of two rational numbers is still rational (so 5-x is rational), and the division by 3 doesn't change this. So, you have that the square root of 8 equals a rational number, which is false. The mistake must have been supposing that was rational, which proves that the sum/difference of the two given terms was irrational
Multiplication/division:
The logic is actually the same: if we multiply the two terms we get
if again we assume x to be rational, we have
But if x is rational, so is -x/15, and again we come to a contradiction: we have the square root of 8 on one side, which is irrational, and -x/15 on the other, which is rational. So, again, x must have been irrational. You can prove the same claim for the division in a totally similar fashion.
Write a system of equation based on the number
For an instance, the two numbers are a and b.
"The sum of two numbers is 59" can be written as follows.
⇒ a + b = 59 <em>(first equation)
</em>"The difference is 15" can be written as follows.
⇒ a - b = 15 <em>(second equation)</em>
Solve the system of equation by elimination/substitution method.
First, eliminate b to find the value of a.
a + b = 59
a - b = 15
--------------- + (add)
2a = 74
a = 74/2
a = 37
Second, substitute 37 as a in one of the equations
a + b = 59
37 + b = 59
b = 59 - 37
b = 22
The numbers are 37 and 22
An equation that sets two fractions equal to each other is called a proportion. A proportion is a name we give to a statement that two ratios are equal. When two ratios are equal, then the cross products<span> of the ratios are equal. Hope this helps.</span>
The answer is C multiply and divide to left to right
The answer is Square pyramid
