A 900 kg satellite moves from a circular orbit 400 km up to one 1400 km up…

Step 1. Energy. $\tfrac12 \times 4.014 \times 10^{14}\ \text{m}^3/\text{s}^2 \times 900\ \text{kg} \times \left(\dfrac{1}{6.8 \times 10^{6}\ \text{m}} - \dfrac{1}{7.8 \times 10^{6}\ \text{m}}\right) = 3.41 \times 10^{9}\ \text{J}$.

Step 2. Speeds. $\sqrt{\dfrac{4.014 \times 10^{14}\ \text{m}^3/\text{s}^2}{6.8 \times 10^{6}\ \text{m}}} = 7.68\ \text{km/s}$ and $\sqrt{\dfrac{4.014 \times 10^{14}\ \text{m}^3/\text{s}^2}{7.8 \times 10^{6}\ \text{m}}} = 7.17\ \text{km/s}$.