Can someone help??? I will give 20 point and brainliest to the first person who answers

Let f(x) = x4- 8x2 . find the relativeextrema of this function using the second derivative test.

Which of the choices below is one of the primary gases found in the atmosphere? a. helium b. carbon dioxide c. nitrogen d. argon

What pressure difference is required between the ends of a 2.0-m-long, 1.0-mm-diameter horizontal tube for 40 c water to flow through it at an average speed of 4.0 m/s?