The value of k is
<h3>How to solve the simultaneous equation?</h3>
Given:
x-y=k.............(eq i)
2x²+y²-15..............(eq ii)
We would make y the subject formula in eq ii
2x²+y²-15= 0
2x² + y²= 15
y²= 15-2x²
y=  ...........(eq iii)
...........(eq iii)
Substitute the value of y into eq i
x-( = k
= k
x- ( = k
= k
k= 
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Answer:
   138.16 in²
Step-by-step explanation:
The surface area SA of the cone is the sum of the base area B and the lateral area LA. The lateral area is half the product of the circumference and the slant height. The radius is half the diameter, so is 4 inches.
   SA = B + LA
   = πr² + (1/2)(2πrh) . . . . where h is the slant height
   = (πr)(r +h)
Filling in the numbers, you have ...
   SA = (3.14)(4 in)(4 in + 7 in) = 3.14×(44 in²) = 138.16 in²
 
        
             
        
        
        
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