This is Adele's solution for the equation x^2 + 8x - 9 = 0 Step 1 x^2 + 8x - 9 = 0 Step 2 x^2 + 8x = 9 Step 3 ( x + 4 )^2 = 25 S

Question

Marina86 [1]

3 years ago

11

This is Adele's solution for the equation x^2 + 8x - 9 = 0 Step 1 x^2 + 8x - 9 = 0 Step 2 x^2 + 8x = 9 Step 3 ( x + 4 )^2 = 25 S

tep 4 x + 4 = 25 or x + 4 = - 25 Step 5 x = 21 or x = - 29. Where did Adele make her mistake. Show all of your work.

Mathematics

2 answers:

dusya [7] · Answer 1 · 2022-03-11T18:58:50+03:00

dusya [7]3 years ago

8 0

The mistake was in step one when she added the 9 to both sides

x^2 + 8x - 9 = 0
__ + __ = 8 (b)
__ • __ = -9 (a•c)
blanks = -1 and 9
(x - 1)(x + 9)
Solve for x in each one
x = 1 or -9

Dmitriy789 [7] · Answer 2 · 2022-03-11T21:28:37+03:00

Dmitriy789 [7]3 years ago

4 0

<h3><em>The mistake was in step 1. Here is how to correctly solve the equation: </em></h3><h3><em>x² - 8x – 33 = 0 </em></h3><h3><em>(x - 11) (x + 3) = 0 </em></h3><h3><em>x – 11 = 0 </em></h3><h3><em>x +3 = 0 </em></h3><h3><em>x = 11 and x = -3</em> </h3>