SOLUTION: In which line is a mistake first made when solving the quadratic equation by completing the square? y2 - 18y + 4 = 70 line 1:y^2 - 18y = 66 line 2:y^2 - 18y + 81 = 66 lin

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: In which line is a mistake first made when solving the quadratic equation by completing the square? y2 - 18y + 4 = 70 line 1:y^2 - 18y = 66 line 2:y^2 - 18y + 81 = 66 lin      Log On


   

Question 1038166: In which line is a mistake first made when solving the quadratic equation by completing the square?
y2 - 18y + 4 = 70
line 1:y^2 - 18y = 66
line 2:y^2 - 18y + 81 = 66
line 3:(y - 9)^2 = 66
line 4:y - 9 = ± √66
line 5:y = 9 ± √66
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The mistake is first made on line 2. The person added 81 to the left side but forgot to add 81 to the right side.

Line 2 should be y^2-18y+81 = 147 (Note: 66+81 = 147)