Question

I need a step by step for how to complete the square on this question

-4x^2 -8x +5

Answer 1

Step 1: -4(x^2+2x)+5 ; grouping by common factor of -4
Step 2: -4(x^2+2x+1-1)+5 ; add and subtract by 1 for preparing sqaure
Step 3 : -4(x^2+2x+1)+4+5 ; remove useless terms in the bracket for making a sqare
Step 4 : -4(x+1)^2+9

Answer 2

I don't understand where the +4 came from in step 3

Answer 3

never mind, I see now