Problem 699

Solve

x2 + 6x -7 = 0 by completing the square.

 

Solution:-

 

Solve for x by first isolating the constant and adding the square of half of the coefficient of x to both sides of the equation.

 

x^2 +6x  -7 + 16 – 16  = 0

x^2 +6x + 9 – 16 =0

(x+3)^{2} = 16

(x+3)^{2} = 4^{2}

x +3 =± 4

x = -3 ± 4

x = -3+4 or -3 – 4

x = 1 ,-7

 

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