Answer: 
<u>Step-by-step explanation:</u>
EQ1: x + y = 12 --> x = 12 - y
EQ2: xy = 15
Substitute x = 12-y into EQ2 to solve for y:
(12 - y)y = 15
12y - y² = 15
0 = y² - 12y + 15
↓ ↓ ↓
a=1 b= -12 c=15

Now, let's solve for x:

Lastly, find x² + y² :



Are you asking what 7 times 3 is? Or what is it you're asking
Answer:

Step-by-step explanation:
Given

Required
Solve
Let

Differentiate



Make dx the subject

The given integral becomes:



Recall that: 
Make
the subject

Square both sides


Substitute
for
in 

Simplify



In standard integration

So, the expression becomes:


Recall that: 

Pharmaceutical companies prefers experimental studies to conducting surveys and observational studies because companies can manipulate or suggest methods easily to have good outcomes and they are able to directly observe the results. Experimental studies is a type of study in which a procedure and method is intentionally introduced.
Answer:
1 1/3
Step-by-step explanation:
3/3 = 1 Whole
Therefore 4/3 = 1 1/3