add b/2A the square of 1/2 of the coefficient of the x term to each side of the equation i dunno how to type it out

What is the value of the digit 1 in the number 13?

15 point ! ~ see if you know the answer to both you!

Δabc is reflected across line l to form δ alblcl, and a¯¯¯al¯¯¯¯ intersects line l at point d. which equation is not necessarily true?