How do you solve # 7x – 7 = 2x + 8#?

2 Answers
Mar 30, 2016

Answer:

#x = 3#

Explanation:

This is solved by simply moving the terms with #x# to the same side and the integers to the same side. You can do this by subtracting #2x# from both sides and adding #7# to both sides. This gives:

#5x = 15#

Then divide both sides by #5#, which gives #x = 3#.

Mar 30, 2016

Answer:

#x=3#

Explanation:

The one rule you must follow is that what you do to one side of the equation you do to the other. Otherwise the 'equals' sign becomes false

Example: #7=7# this is true as the value on both sides is the same.

If I apply #7-2=7# this becomes false as we have 5=7 which is not true. How ever

#7-2=7-2# is true. We have applied the action to both sides.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is why what I wrote is important:

Given:#" "color(brown)(7x-7=2x+8)#

Subtract #color(blue)(2x)# from both sides

#" "color(brown)(7xcolor(blue)(-2x)-7=2xcolor(blue)(-2x)+8)#

But #2x-2x =0#

#" "5x-7=0+8#

Add #color(blue)(7)# to both sides

#" "color(brown)(5x-7color(blue)(+7)=8color(blue)(+7)#

But # -7 +7 = 0#

#" "5x+0=15#

Divide both sides by #color(blue)(5)#

#" "color(brown)(5/(color(blue)(5)) x=15/(color(blue)(5)))#

But #5/5=1" and "15/5= 3#

#" "color(magenta)(x=3)#

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~