I’ve tried imputing the numbers but apparently I’m doing wrong so help please

Answer:
CB = sqrt (4a^2 + 6b^2)
Step-by-step explanation:
Using distance formula
d^2 = ( x1-x2)^2 + (y1-y2)^2
d^2 = (3a - -a)^2 + (b - -5b )^2
d^2 = (4a)^2 + (6b)^2
Answer: [tex]CB = \sqrt{16a^2 + 36b^2}\\\\[/tex]
Work Shown:
[tex]d = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}\\\\CB = \sqrt{(3a-(-a))^2 + (b-(-5b))^2}\\\\CB = \sqrt{(3a+a)^2 + (b+5b)^2}\\\\CB = \sqrt{(4a)^2 + (6b)^2}\\\\CB = \sqrt{16a^2 + 36b^2}\\\\[/tex]
If that doesn't work, then your teacher may only want the stuff in the green box. So that would be either b-(-5b), or b+5b, or 6b