Here are two steps from the derivation of the quadratic formula. x^2 + b/a x = - c/a
x^2 + b/a x + (b/2a)^2 = - c/a + (b/2a)^2
what took place between the first step and the second step?

Explanation is in the file

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pakistan's principal natural resources are arable land and water. about 25% of pakistan's agriculture accounts for about 21% [1] of gdp and employs about 43% of the labour force. in pakistan, the most agricultural province is punjab where wheat and cotton are the most grown.