How do you check a linear equation and find if 7 is a solution to #5x-5=30#?

1 Answer
Feb 5, 2015

In general, to evaluate any function #f(x)# in a specific point, you simply need to substitute every #x# with that specific value.

In your case, rather than evaluating a function, you want to check an identity. The spirit is the same, you only need to substitue #x \rightarrow 7#, and see if you obtain a true statement, or a false one.

Substituting, we have
#5x-5=30 \rightarrow 5\cdot 7 -5 =30 \iff 35-5=30 \iff 30=30#
which is of course true.