Suppose I have four equations for four variables $$a+b+c+d=0$$ $$5a+3b+2c+6d=10$$ $$12a+21b+c+4d=30$$ $$2a+3b+4c+5d=40$$
Now what is the fastest way to find a, b, c and d?
I know of elimination and substitution out of which elimination takes lesser time. Is there any faster way than that?
I took these equations (which are written above) arbitrarily.