Question

Part A: Explain why the x-coordinates of the points where the graphs of the equations y = 4-x and y = 2x + 3 intersect are the solutions of the equation 4-x = 2x + 3.
Part B: Make tables to find the solution to 4-x = 2x + 3. Take the integer values of x between -3 and 3.
Part C: How can you solve the equation 4-x = 2x + 3 graphically?

Answer 1

Part A: Explain why the x-coordinates of the points where the graphs of the equations y = 4-x and y = 2x + 3 intersect are the solutions of the equation 4-x = 2x + 3.

Because the point where the graphs intersect is a point that meets both rules (functions) y = 4 - x and y = 2x + 3 meaning that y from y = 4 - x equals y from 2x + 3 and also both x have the same value.

Part B: Make tables to find the solution to 4-x = 2x + 3. Take the integer values of x between -3 and 3.

x values    4 -x         2x + 3

-3              4-(-3)=7     2(-3)+3 =-3
-2              4-(-2)=6     2(-2)+3 =-1
-1              4-(-1)=5     2(-1)+3 = 1
0                4-0=4        2(0)+3 = 3
1                4-1=3         2(1)+3=5
2                4-2=2        2(2)+3 = 7
3                4-3=1        2(3)+3 = 9

The the solution is between x = 0 and x =1

Part C: How can you solve the equation 4-x = 2x + 3 graphically?

Draw in a same graph both functions  y= 4 - x and y = 2x +3.

Then read the x-coordinates of the intersection point. That is the solution.