How do i find the volume in 3d shapes, please help i need to get better grades

Solve the system by the elimination method. 2x + y - 4 = 0 2x - y - 4 = 0 when you eliminate y, what is the resulting equation? a.x = 0 b.4x = -8 c.4x = 8

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)

The table below shows the approximate height of an object x seconds after the object was dropped. the function h(x)= -16x^2 +100 models the data in the table. for which value of x would this model make it the least sense to use? a. -2.75 b. 0.25 c. 1.75 d. 2.25