Powers And Standard Form
1. Stating the problems:
(a) Find the value of $\left( \frac{1}{4} \right)^{0.5}$.
(b) Find the value of $(-8)^{\frac{2}{3}}$.
(c) Calculate $2 \times 10^{100} - 2 \times 10^{98}$ and express the answer in standard form.
2. Solve (a):
Recall that raising a number to the power $0.5$ is equivalent to taking its square root:
$$\left( \frac{1}{4} \right)^{0.5} = \sqrt{\frac{1}{4}} = \frac{\sqrt{1}}{\sqrt{4}} = \frac{1}{2}$$
3. Solve (b):
Write $-8$ as $-8 = - (2^3)$. We use the property of exponents:
$$(-8)^{\frac{2}{3}} = \left( -(2^3) \right)^{\frac{2}{3}} = \left(-1\right)^{\frac{2}{3}} \times \left(2^3\right)^{\frac{2}{3}}$$
Since $\left(-1\right)^{\frac{2}{3}} = \left((-1)^2\right)^{\frac{1}{3}} = 1^{\frac{1}{3}} = 1$.
And by the power of a power rule:
$$\left(2^3\right)^{\frac{2}{3}} = 2^{3 \times \frac{2}{3}} = 2^2 = 4$$
Therefore:
$$(-8)^{\frac{2}{3}} = 1 \times 4 = 4$$
4. Solve (c):
Start with the expression:
$$2 \times 10^{100} - 2 \times 10^{98}$$
Factor out $2 \times 10^{98}$:
$$2 \times 10^{98} \left(10^2 - 1\right) = 2 \times 10^{98} \left(100 - 1\right) = 2 \times 10^{98} \times 99 = 198 \times 10^{98}$$
Express in standard form by converting $198$ into $1.98 \times 10^2$:
$$198 \times 10^{98} = 1.98 \times 10^2 \times 10^{98} = 1.98 \times 10^{100}$$
Final answers:
(a) $\frac{1}{2}$
(b) $4$
(c) $1.98 \times 10^{100}$