Answer : 
Given expression is 
To make perfect square trinominal we use completing the square method
In completing the square method we add and subtract the half of square of coefficient of middle term
Here coefficient of middle term is -7
Half of -7 is 
Square of
is
=
So the expression becomes
that gives perfect square trinomial
Hence , the value of 'c' is
Answer:
This is a sphere with a center
and radius 
Step-by-step explanation:
Given that: (x,y,z)
where;
d₁ is the distance from the origin = 
d₂ is the distance from (2,2,2) = 
Also;
d₁ = 2d₂

By squaring both sides;




Collect the like terms:


Divide both sides by 3


Using the completing the square method;


∴
This is a sphere with a center
and ;
radius; 

Answer:
$27.50
Step-by-step explanation:
Hope this helps and have a great day!!!!
This is fairly simple. Just do 2x15 to get your answer 2x15=30. Explanation if it is 2 times longer you would do 2 and then when it says it is 15 diagonal that is where the 15 comes in and it would be 2x15. So your answer is 30