The square of 9 less than a number is 3 less than the number. What is the number? -12 or 7
-12 or -7
1-7 or 12
7 or 12

7, 12

Step-by-step explanation:

( n-9)^2 = n-3

Foil the right

n^2 -18n +81 = n-3

Subtract n from each side

n^2 -19n +81 =-3

Add 3 to each side

n^2 -19n +84 = 0

Factor

What 2 numbers multiply to 84 and add to -19

-12*-7 = 84

-12+-7 = -19

( n-7) (n-12) =0

Using the zero product property

n-7 =0   n-12= 0

n=7  n=12

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.