Respuesta :

khtoure353
the value of a/b = 2.5 because a = 5 and b = 2.

if a^2 - b^2 = 21,
5^2 = 25, 2^2 = 4,
25 - 4 = 21

if a - b = 3,
5 - 2 = 3

5/2 = 2.5

hope this helps! :)
mathstudent55

Answer:

a + b = 7

Step-by-step explanation:

a^2 - b^2 = 21

Factor the left side. It is the difference of two squares which factors into the product of a sum and a difference.

(a + b)(a - b) = 21

We are told a - b = 3, so substitute 3 for the factor a - b.

(a + b)(3) = 21

Divide both sides by 3.

a + b = 7

good job