Question

Solve the following system of equations by linear combination: 2d + e = 8 d – e = 4

Answer 1

Because there is a +e and a -e in the two equations we can simply add them together to solve for d...

2d+e+d-e=8+4  combine like terms

3d=12 divide by 3

d=4,  now use this d in either original equation to solve for e...d–e=4 so

4-e=4 subtract 4

-e=0 

e=0

So the solution, where the lines intersect graphically, is the point (4, 0)