Answer:
x = 2 ± [tex]\sqrt11}[/tex]
Step-by-step explanation:
Given
x² - 4x - 7 = 0 ( add 7 to both sides )
x² - 4x = 7
To complete the square
add (half the coefficient of the x- term)² to both sides
x² + 2(- 2)x + (- 2)² = 7 + (- 2)²
(x - 2)² = 7 + 4 = 11 ( take the square root of both sides )
x - 2 = ± [tex]\sqrt{11}[/tex] ( add 2 to both sides )
x = 2 ± [tex]\sqrt{11}[/tex] ← exact solutions
