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Solve ax+b = cx + d
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Solving Linear
Equations
(Feb 14, 2005)
with & then without stick diagrams plus   solving word problems; and solving systems: -  essentially one unknown, essentially triangular & general

 

Solve 4x + 10 =  30
Solve 3x -4 = -11
(¼)x = x - 9
Solve ax+b = cx + d


Read them in order

(i) x + 20 = 29 WS
(ii) 2x + 6 = 24 WS
(iii) 3x + 10 = 32 WS
(iv) 5a + 16 = 3a+ 24 WS
(v)  (½)x + 8 = 24½ WS
(vi)  (¾)a + 16 = (¼)a+ 24 WS
(vii) (¾)q + 17 = 32 WS
(viii) 13 =[2/3]x +7 twice WS
(5/6)q + 8+(5/6) = 14 + (2/3) WS
Proper Use of Equal Sign


Up
Solve 4x + 10 =  30
Solve 3x -4 = -11
(¼)x = x - 9
Solve ax+b = cx + d
 


If you do not follow the use of parameters below, do not worry.   Take peak at Chapters 15 in Three Skills for Algebra. It will give you a second perspective on solving linear equations starting with examples simpler than you have mastered in this site area, but that second perspective also may also help you understand the following example.  It is an example from the end of Chapter 15.

Example 1: Solve ax+b = -cx+d

See Animation below

Find an expression for x which solves the equation

ax+b = -cx+d

Look at the solution before and see if you understand it. If not, do not worry, the preparation for understanding it is incomplete.  If you do not follow all the steps, you may visit Chapters 8 to 15 in the online book Three Skills for Algebra. Chapters 15 may be the most useful.
Operation Equation
given ax+b = -cx+d
add -b to both sides ax = -cx+d - b
add cx to both sides ax +ac = d - b 
Apply distributive law in
reverse (factor x)
(a+c)x = d - b 
Divide both sides by (a+c) if
a+c is non zero.
x =  d-b
a+c 

See if you can check that 
x =  d-b
a+c 

satisfies the original equation ax+b = -cx+d.

 
 

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