A few examples:
4x+5y
1232x + 564y + 5354z - 7642 a
Basically any number with a variable that you can not use again.
        
                    
             
        
        
        
Answer:
A) 5
B) 4
C) 3
D) 64
Step-by-step explanation:
correct on edge
 
        
             
        
        
        
Answer:
x=4
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer: 
Step-by-step explanation:
Given: The side of the square shaped traffic sign = 4x+3
We know that the area of square is given by:-

Therefore, the area of the side of the square shaped field is given by:-

We know that , 
Therefore, 

Hence, 
 
        
                    
             
        
        
        
Answer:
D. Pythagorean
Step-by-step explanation:
Given the identity
 cos²x - sin²x = 2 cos²x - 1.
To show that the identity is true, we need to show that the left hand side is equal to right hand side or vice versa.
Starting from the left hand side
cos²x - sin²x ... 1
According to Pythagoras theorem, we know that x²+y² = r² in a right angled triangle. Coverting this to polar form, we have:
x = rcostheta 
y = rsintheta
Substituting into the Pythagoras firnuka we have
(rcostheta)²+(rsintheta)² = r²
r²cos²theta+r²sin²theta = r²
r²(cos²theta+sin²theta) = r²
(cos²theta+sin²theta) = 1
sin²theta = 1 - cos²theta 
sin²x = 1-cos²x ... 2
Substituting equation 2 into 1 we have;
= cos²x-(1-cos²x) 
= cos²x-1+cos²x
= 2cos²x-1 (RHS)
This shows that cos²x -sin²x = 2cos²x-1 with the aid of PYTHAGORAS THEOREM