Find the nth term for this quadratic sequence

84

from 4 to 7 , they added 3

from 7 to 12 they added 5

from 12 to 19 they added 7

from 19 to 28 they added 9

3, 5, 7, 9 They are simply adding odd numbers to each number. So after 9 would be 11, so you add 11 to 28 and get 39, and so on...

39 + 13= 52

52 + 15 = 67

67 + 17 = 84

84 is the ninth term, so that is your answer.  

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.

h= 12 inches

step-by-step explanation: