Posted by john on .
My math teacher wants us to prove that all of our answers are correct.
But how am I supposed to be able to prove stuff, like this, for example.
The directions want you to write out the words in to an equation.
Seven is the sum of X and 5.
so my answer is 7= x +5
How would I prove my answer?

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Ms. Sue,
Doesn't x = 2? Substitute 2 for x.
Doesn't 7 + 2 = 7? 
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john,
We're not supposed to figure out what the variable is.
The direction for the question was to write out the sentence in an equation 
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jim,
The question wants you to figure out what number replaces X.
7 = x + 5
7 = ? + 5.
What number replaces x, or the questionmark? You're going to write:
x = (some digit, which is your answer)
Proving is easy. Just write
7 = x + 5 down again, but this time replacing x with your answer. 
math 
jim,
Oh.
If it's any comfort, I have no idea how writing sentences embodying equations could be proven, either.