91Ó°ÊÓ

The number of cell telephone subscribers in the United States from \(1995-2010\) can be modeled by \(f(x)=25 x^{23 / 25},\) where \(f(x)\) is the number of cellular telephone subscriptions in millions, \(x\) years after \(1995 . \text { (Source: CTIA-Wireless Association, } 1995-2010)\) Use this information to answer. Predict the number of cellular telephone subscriptions in \(2015 .\) Round to the nearest tenth of a million.

Find and correct the error. See the Concept Check in this section. $$ \frac{\sqrt[4]{16}}{\sqrt{4}}=\sqrt[4]{\frac{16}{4}}=\sqrt[4]{4} $$

Simplify. $$ (8-\sqrt{-4})-(2+\sqrt{-16}) $$

The number of cell telephone subscribers in the United States from \(1995-2010\) can be modeled by \(f(x)=25 x^{23 / 25},\) where \(f(x)\) is the number of cellular telephone subscriptions in millions, \(x\) years after \(1995 . \text { (Source: CTIA-Wireless Association, } 1995-2010)\) Use this information to answer. Explain how writing \(x^{-7}\) with positive exponents is similar to writing \(x^{-1 / 4}\) with positive exponents.

Suppose a classmate tells you that \(\sqrt{13} \approx 5.7 .\) Without a calculator, how can you convince your classmate that he or she must have made an error?

Simplify. Determine whether \(2 i\) is a solution of \(x^{2}+4=0\)

Simplify. See a Concept Check in this section. Assume variables represent positive numbers. $$ \sqrt[5]{x^{35}} $$

Simplify. See a Concept Check in this section. Assume variables represent positive numbers. $$ \sqrt[6]{y^{48}} $$

Simplify. Determine whether \(-1+i\) is a solution of \(x^{2}+2 x=-2\)

Suppose a classmate tells you that \(\sqrt[3]{10} \approx 3.2 .\) Without a calculator, how can you convince your friend that he or she must have made an error?