Question

This is Adeles solution for the equation x^2+8x- 9 = 0 Step 1 x^2 +8x = 9 Step 2 x^2 +8x + 16 = 9 + 16 Step 3 ( x + 4 ) ^2 = 25 Step 4 x + 4 = 25 or x + 4 = - 25 Step 5 x = 21 or x = - 29. Where did Adele make her mistake? What are the solutions to this equation? Show all of your work. 2. Which would be the best method to use to solve the following equation. Explain your reasoning. A x^2 - 49 = 0 B. x^2 - 3x - 4 = 0 C. x^2 - 2x - 6 = 0 ​

Answer 1

Adeles forgot to square root 25 in step 4 therefore the solutions would be 1 and -9

Explanation:

Equation : x² + 8x - 9 = 0

Step 1 : x² + 8x = 9

Step 2 : x² + 8x + 16 = 9 + 16

Step 3 : ( x + 4 )² = 25

Step 4 : x + 4 = 25 or x + 4 = - 25

Step 5 : x = 21 or x = - 29.