Answer:
x=1/2
Step-by-step explanation:
8(x-3)+7=2x(4-17)
8(x-3)+7=2x(-13)
This is where Lin's first mistake appears, 4-17 is -13, not positive 13.
Next, Lin distributes.
8x-24+7=26x
This is right with Lin's equation, since Lin got 13 instead of -13.
However, if we were doing it correctly from the start, it should be:
8x-24+7=-26x
Okay, after 8x-24+7=26x Lin simplifies again to:
8x-17=26x
She then tries to eliminate 8x.
What she does wrong here, is that she subtracts 8x from the left, and adds 8x to the right.
This makes it so that the equation is not equal anymore, because what you do to one side, you must do to the other.
This is Lin's second mistake.
What she should have gotten is
-17=18x.
Okay, now that we have found her mistakes, let's solve this correctly.
8(x-3)+7=2x(4-17)
8(x-3)+7=2x(-13)
Distribute.
8x-24+7=-26x
8x-17=-26x
Add 17 to both sides.
8x=-26x+17
Add 26x to both sides.
34x=17
x=1/2
Her answer should have been 1/2.
