Difference between permutation and combination

The difference is that permutation is an arrangement where order is important while combination is a selection and order is not important. Think of a sandwich made from a slice of bread, an omelette and salad. You can arrange the three ingredients in the following order (assume you are laying the sandwich on the plate); a) bread, omelette,salad b) bread, salad, omelette c) salad,bread, omelette d) salad, omelette, bread e) omelette, bread, salad f) omelette,salad, bread The above is 6 arrangements (permutations). Now, assume 6 people ordered (a) to (f) sandwiches for breakfast, would they be right to say they ate 6 different types of sandwiches? of course NOT!It is just one COMBINATION (selection) of sandwich.

Solving system of linear equations

One can solve a system of linear equations using substitution method, elimination method, graphical method, crammer's rule among others. Some websites offer applications/solver that show you how to work out the sum.  One can get a variety of resourceful sites if you are good in research skills. As long as you know exactly what you are searching for,and you are patient, inquisitive and curious enough,and also you do not have a phobia for computers, then you have no problem as long as you can make use of the google search engine.For the time being, it basically has enough for you.

'Stop passing the buck'

'Do you like what you are doing now? If not, then stop doing it now. It is said that, ‘if you find yourself digging a hole, then the best thing you should do, is simply stop digging’. If you find yourself complaining about a situation you are in and expecting somebody else to come and better the situation for you, then brace yourself for future frustrations. Learn to manage your environment. Your environment is both intrinsic and extrinsic. You are like a plant. For you to thrive, you need the right nutrients and the right environment. Unlike the plant, you can control all these. Your thoughts reflect you. The thoughts you entertain form your environment that influence you. It is you to act on the right environment'. An excerpt from, 'Reflections'by kahenya,np

Conics

Circles, parabolas, ellipses and Hyperbolas are collectively called conic sections.The general equation of conic sections is Ax^2+By^2+Cxy+Dx+Ey+F=0. You can google and get valuable links on conic sections.

Solving Linear Systems

In your previous classes at primary and high school levels, you came across linear equations i.e. equations whose functions if plotted on a plane or graph paper you will end up getting straight lines. Linear equations may have one or more unknowns. For instance; x=3;y=-5;x+y=5;x+y+2z=6;2a+3b+3c-6d=7 and so on. Solving linear equations with 1 unknown and 4 or more unknowns will not be discussed here. Our interest is to solve linear equations with 2 and 3 unknowns. Some quantities in real life may be expressed in linear form, but in reality it is rare to have linear relationships because of the many parameters that are in play. Linear equations are used in real life to explain situations while holding some variables constant. For instance price p of a commodity say a phone may partly depend on demand q of the phones and partly constant. Note, the price cannot go down to zero even if the demand is zero. This may be written as p=bq+k.