I think of a number, add seven, then divide by 5. What is the equation

Find the value of the variable and the length of each secant segment.

The magnitude, m, of an earthquake is defined to be m=log l/s, where i is the intensity of the earthquake (measured by the amplitude of the seismograph wave) and s is the intensity of a “standard” earthquake, which is barely detectable. what is the magnitude of an earthquake that is 1,000 times more intense than a standard earthquake? use a calculator. round your answer to the nearest tenth.

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.