Xsquared plus 2 x equals 15
x2+2x=15
what number should be added to both sides of the equation to complete the square?

Given  

x 2 − 2 x = 15

add 1 to both sides to get:

6 = x 2 −

2 x + 1 = ( x − 1 ) 2

So  x − 1 = ± √ 16 = ± 4

Add  1  to both sides to get:

x = 1 ± 4

That is:  x = − 3

or

x = 5

step-by-step explanation:

we can use this expression to calculate the energy gain as a particle moves with a field or the energy loss as it moves against it. (note that it is also used to define the electron-volt, a unit of energy equal to that gained by an electron as it falls through a pd of 1 v, i.e. w = 1 ev = 1.6 10-19 c 1 v = 1.6 10-19j).in fact this expression is really nothing more than the statement that potential is the potential energy per unit charge. in this case, v= w/qis simply stating that the change in potential energy(or work done) per unit charge is equal to the change in potential (or potential difference), v.student questions: uniform electric fields2electron beamcathode+5 kvanode0 v