The equation x2 − 9 = 0 has real solution

Work Shown:

x^2 - 9 = 0

x^2 - 3^2 = 0

(x-3)(x+3) = 0 difference of squares rule

x-3=0 or x+3=0

x = 3 or x = -3

4 and 5)16.97 or 12√2

6)15.59 or 9√3

7)y = 15.59 or 9√3     x =27

8)17.80

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.