Question

9. Solve graphically: x + y = 4 and x - y = 8.​

Answer 1

The solution is x=6, y=2: See explanation below.

Explanation:

To solve such a system you should regard each equation as a function of x and y, where

x1+y1=8 , or y1=−x1+8

To be able to plot the graph you will note that x=0 gives y=8, and y=0 gives x=8, so the two points (0, 8) and (8, 0) are on the line.

x2−y2=4 , or y2=x2−4

x=0 gives y=-4, and y=0 gives x= 4, so this line must go through the points (0, -4) and (4, 0)

The point you are interested in, has to be on both lines at the same time, i.e. it must be where the two lines cross. The graph shows that the two lines cross in (6,2), i.e. x=6, y=2, which, therefore, is the solution you want.

It is always good to check the solution one has got by incerting the found value in the two equations:

x+y=8⇒6+2=8 Check

x−y=4⇒6−2=4 Check

Step-by-step explanation:

i hope this is helpful for you