Answer:
a = 1/2; b = -29/4
Explanation:
x^2x-7=(x+a)^2 +b
There's a missing sign between x^2 and x. I assume this is the problem:
x² + x - 7 = (x + a)² + b
We need to complete the square on the left side.
x² + x - 7 =
= (x² + x + 1/4) - 7 - 1/4
= (x + 1/2)² - 29/4
= (x + a)² + b
a = 1/2; b = -29/4