Math Answers

find dy/dx when y= "(1+x\/1-x)" ^-2

An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed, with mean equal to 786 hours and a standard deviation of 80 hours. Find the probability that a random samples of 17 bulbs will have an average life between 799 and 802 hours.

Let A, B be two subrings of a ring R such that for all a e A, b e B,

ba e A then show that

(1) A + B is a subring of R.

(2) A is an ideal of A + B.

3) An B is an ideal of B.

If A,B C are three ideals of a ring R then show that A(BC)=(AB)C

Show that a ring can't be expressed as union of 2 proper ideals but it is possible to express it as a union of three proper ideals

1.      One of the undersecretary of the Department of Labor and Employment (DOLE) claims that the average salary of Social worker is Php18, 000. A sample of 19 social worker’s salary has a mean of Php17, 350 and standard deviation of Php1, 230. Is there enough evidence to reject the undersecretary’s claim at 𝛼 = 0.01?

Formulate the differential equation representing the relationship of current (i), voltage (v), inductance(L) and time t.

Use the following cell phone airport data speeds​ (Mbps) from a particular network. Find P80.

Find all possible Taylor's series and Laurent series expansions of f(z) = (2z-3) /(z-2) (z-1) about z=0?

What is the integral of 1/(z-1) (z-2) (2-4) dz where C is |z| = 3?