Equasions Ineq and Vics strategy guide

[sanyu4]

From Equations Ineq and Vics strategy guide, page 63 number 3. I understand how that you have to set the equation to 9, but how do you get (a + b)^2 as the answer from (A^2+ B^2), I get: A^2 + 4ab + b^2 = 9?

Thank you

[jnelson0612]

sanyu, the original problem says A^2 + B^2 + 2AB; rewrite that as A^2 + 2AB + B^2. Do you now see how we can factor that to (A+B)(A+B) or (A+B)^2?