Suppose the government in this economy decides to decrease government purchases by $350 billion. The decrease in government purchases will lead to a decrease in income, generating an initial change in consumption equal to . This decreases income yet again, causing a second change in consumption equal to . The total change in demand resulting from the initial change in government spending is .

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.