2resistors of resistance, r = (100 +- 3) ohm, r2 = (200+-4)ohm are connected in parallel and series.

find the absolute error and % error in the measurement of equivalent resistance are in each combinations i. e series and parallel.. ? ?

According to what I've learnt, in any expression of multiplication or division, the percentage errors of each term are added up to find the equivalent percentage error. That is, if

y=ABC

y=ABCthen% error in y= % error in A + % error in B + % error in C

For the above problem, let Rs denote series combination. Then Rs=300±7 ohm.

Let Rp denote parallel combination.

∴Rp=R1R2/R1+R2 = R1R2/Rs

Ignoring errors, we get Rp=200/3 = 66.67 ohm

%error in R1=3, %error in R2=2, %error in Rs=7/3

Hence, %error in Rp=3+2+7/3=22/3

So, error in Rp will be 22/3% of 200/3, which is approximately 4.89.

Hence, I got Rp=66.67±4.89 ohm.

However, the book used the formula described and proved here and arrived at the answer Rp=66.67±1.8ohm.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.

One splits the atoms and molecules  the other combines them