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Solve the equation
x2 + 4x - 7 = 0
by completing the square.
Give your answers correct to 2 decimal places.​


Sagot :

Answer:

x ≈ - 5.32, x ≈ 1.32

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 + 4 = 7 + 4

(x + 2)² = 11 ( take the square root of both sides )

x + 2 = ± [tex]\sqrt{11}[/tex] ( subtract 2 from both sides )

x = - 2 ± [tex]\sqrt{11}[/tex]

Then

x = - 2 - [tex]\sqrt{11}[/tex] ≈ - 5.32 ( to 2 dec. places )

x = - 2 + [tex]\sqrt{11}[/tex] ≈ 1.32 ( to 2 dec. places )