Answer:
option (2) is correct.
is in the scientific notation form.
Step-by-step explanation:
Given: Some expressions
We have to choose which expressions is written in scientific notation.
For an expression to be in scientific notation the most important requirement is that the whole number is between 1 and 10, but not including 10.
that is , 1 ≤ a < 10 and n is integer.
Thus, out of given only is in the scientific notation form.
Thus, option (2) is correct.
Answer:
The age of each person is:
Step-by-step explanation:
To solve this problem you must make two equations. First, we name Jess and Mac as variables:
j = Jess age.
m = Mac age.
Now we make the equations, the first equation has the information "Jess is 12 years less than half as old as Mac":
1.
The second equation has the information "The sum of their age is 87":
2.
Now, we replace the first equation in the second one:
And we operate:
We clear the variable m:
How we know Mac's age is 66 years old, we can identify Jess' age with the second equation:
We replace the value of m:
And clear the variable j:
In the end, Jess's age is 21 years old.