Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
5. Solving Equations by Graphing
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Exercise 2 Page 244

Create functions from the left-hand and right-hand sides of the equation.

x=0.5

Practice makes perfect
To graph the equation - 4+9x=- 3x+2, we create two functions out of the left- and right-hand sides of the equation. f(x)=- 4+9x and g(x)=- 3x+2 The x-coordinate where the graphs of these functions intersect is the solution to our equation. Since the given equations are not in slope-intercept form, let's rewrite them so that it will be easier to identify their slopes and y-intercepts.
y=- 4+9x
y=9x-4
Now, let's graph these lines.
Point of intersection
The graphs intersect at x=0.5, which is our solution. We can verify this algebraically by solving the equation.
- 4+9x=- 3x+2
9x=- 3x+6
12x=6
x=6/12
x=0.5
To check this solution, we will substitute it back into the given equation and simplify. If doing so results in a true statement, our solution is correct.
-4+9x=- 3x+2
-4+9( 0.5)? =- 3( 0.5)+2
-4+4.5? =- 1.5+2
0.5=0.5 âś“