Answer:
(5,-3)
Step-by-step explanation:
9x+2y=39
6x+13y=-9
---------------
117x+26y=507
12x+26y=-18
----------------------
105x=525
x=5
Substitution
9(5)+2y=39
45+2y=39
2y=-6
y=-3
Answer:
see explanation
Step-by-step explanation:
Using the trigonometric identity
sin²x + cos²x = 1 , then
sin²x = 1 - cos²x and cos²x = 1 - sin²x
Consider the left side
← expand numerator/denominator using FOIL
=
= 
= 
= 
= cot²A = right side , thus proven
Answer:

Step-by-step explanation:
Given

Required
Determine 

Open bracket

Equate the equation to 0

Express 3 as 1 + 1 + 1

Collect like terms

Group each terms

Factorize (starting with the first bracket)












Express 0 as 0 + 0 + 0

By comparison



Solving for 
Take square root of both sides

Add 1 to both sides


Solving for 
Take square root of both sides

Subtract 1 from both sides


Solving for 
Take square root of both sides

Subtract 1 from both sides


Substitute the values of a, b and c in 



B because it’s the only one that doesn’t double in value
Find the GCF of 15 and 35
15=3*5
35=7*5
The Greatest Common Factor here is 5
Divide both the numerator and denominator by this value to get the simplest form.
15/5=3
35/5=7
Final answer: 3/7