Question

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This is Jovan’s solution for the equation x^2-8x-9=0:

x2 – 8x – 9 = 0

x2 – 8x = 9

x2 – 8x + 16 = 9 + 16

(x – 4)2 = 25

x – 4 = 25 and x – 4 = - 25

x = 29 and x = -21

Is Jovan’s solution correct?

Answer 1

• No

Explanation:

• x² – 8x – 9 = 0
• x² – 8x = 9
• x² – 8x + 16 = 9 + 16
• (x – 4)² = 25
• x – 4 = 25 and x – 4 = - 25 ⇒ Incorrect, should be x - 4 = 5 and x - 4 = -5
• x = 29 and x = -21 ⇒ Incorrect, should be x = 9 and x = -1

Answer 2

No, it's wrong

`{x}^(2) - 8x - 9 = 0 \\ (x - 9)(x + 1) = 0 \\ x = 9 \: and \: - 1`