Need Some help with Daughter's Geometry?

Question

I'm trying to help my daughter with her geometry homework and we are both lost. She figured everything out but this one:

a^2 + 2a + 1 = 9

Thanks for your help.

Answer 1

Geometry or Algebra?

a^2 + 2a + 1 = 9

=> a^2 + 2a - 8 = 0

=> (a + 4)(a - 2) = 0

=> a = -4 or 2

Answer 2

a^2 + 2a + 1 = 9 (factor left side of equation by finding two integers that give a product of 1, but add to equal 2, which are 1 and 1)

(a + 1)(a + 1) = 9

(a + 1)^2 = 9 (square root both sides)

a + 1 = 3 or a + 1 = -3 (subtract 1 from both sides)

a = 2 or a = -4 <===ANSWER

Answer 3

The answer would be a=2 because 2 times 2 equals 4.  

That is added to itself to make 8.  Plus 1 equals 9.  

Answer 4

2 or -4

Answer 5

a^2 + 2a + 1 = 9

a^2 + 2a -8 = 0

(a+4)(a-2) = 0

a+4 = 0 OR a-2=0

a = -4 OR a = 2

Answer 6

thats so easy, a=4

Answer 7

a^2 + 2a + 1 = 9

(a+1)^2=9

a+1=sqr9

a=sqr9-1

a=-3-1=-4, a=3-1=2