Question

Find the value of B?
y=-x²+bx - 1

Answer 1

b= 2 if you need a perfect square

Explanation:

If we need to "Find the value of b? " so that the quadratic equation can be written as a perfect square

y= -x²+bx - 1, factor the -1

y= - (x² -bx +1), we know (a+b)² = a²+2ab+b² = x²-bx+1 , so b must be 2

y= - (x² -2x +1), rewritten as a perfect square

y= - (x -1)²