- \(x^{2} + x-20 = (x-4)(x+5)\)
2. \(10.5(1+r)^{30}\)
3. \((6.71 \times 10^{8}) \times (2.3 \times 10^{-4}) \approx 1.54 \times 10^{5}\)
4. \(\pi{L}(1-\alpha)R^{2}=4\pi\sigma T^{4}R^{2}\)
5. \( 56 mi \times \frac {1.61km}{1 mi} \approx 90 km\)
6.\[56\text{mi} \times \frac {1.61 \text{km}}{1 \text{mi}} \approx 90 km\]
7.\( $10,000,000 \times (0.98) ^{100} \approx 90 km\)
8.\(7,681,118,346 \approx 7, 700,000,000 = 7.7 \times 10^{9}\)
9.\[ 150\text{m} \times \frac{ 4.5 \times 10^{6} \text {kg}}{1 \text{sec}} \times \frac{10J}{1 \text{kg}\times 1 \text{m}} = 6.75GW\]