Question 1: We have to identify which of given expressions are rational expressions.
1. Â [tex]3.12 \times 1.4[/tex]
= 4.368
= [tex]\frac{4368}{1000}[/tex]
This is expressed in the form of [tex]\frac{p}{q}[/tex] where p and q are integers, where q is not equal to zero.
Hence, it is rational.
2. [tex]\sqrt 9 \times \sqrt 25[/tex]
= [tex]3 \times 5[/tex]
= 15
= [tex]\frac{15}{1}[/tex] which is also expressed in the form of [tex]\frac{p}{q}[/tex] where p and q are integers, where q is not equal to zero.
Hence, it is rational.
3. [tex]\sqrt 2 \times \sqrt 3[/tex]
= [tex]\sqrt 6[/tex]
which can not be expressed in the form of [tex]\frac{p}{q}[/tex] where p and q are integers and q is not equal to zero.
Hence, it is not rational.
4. 4+5
= 9
= [tex]\frac{9}{1}[/tex] which is also expressed in the form of [tex]\frac{p}{q}[/tex] where p and q are integers, where q is not equal to zero.
Hence, it is rational.
5. [tex]n \times 3[/tex]
This expression can be rational and can not be rational. It depends on the value of 'n'.
Question 2:
Molli purchased 9 apples for $3.96.
Then, Molli divided $3.96 by 9.
Since, the cost of 9 apples = $3.96
If we have to find the cost of 1 apple, then we will divide the cost of 9 apples by the number of apples purchased.
Therefore, Cost of 1 apple = $3.96 [tex]\div 9[/tex]
= 0.44
Therefore, Molli divided $3.96 by 9 in order to find out how much she paid per apple.
Therefore, Option 1 is the correct answer.
