What must be added to #3x -7# to make it #x^2+4x-1#?

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Answer 1 · 2017-05-22T21:02:29

You need to add: #" "x^2+x+6#

Let the unknown part be represented by #A#

Then we have: #" "3x-7+A=x^2+4x-1#

Subtract #3x# from both sides

#-7+A=x^2+4x-3x-1#

but #4x-3x# is #x#giving:

#-7+A=x^2+x-1#

Add 7 to both sides

#A=x^2+x+6#

So you need to add: #x^2+x+6#