Question

Let m=2x+3m=2x+3m, equals, 2, x, plus, 3.

Answer 1

Answer:

$m^2-m=0$

or  $m^2=m$

Step-by-step explanation:

you have a definition for the variable m:

$m=2x+3$

and then you are asked to find the equivalent equation to:

$(2x+3)^2-14x-21=-6(2x+3)$

in terms of m, what we need to do is substitute all the $2x+3$ we find in the expression, for an m (because of the definition $m=2x+3$), this way we get the following:

$m^2-14x-21=-6m$

we still have to write $-14x-21$ in terms of m for that we factor a -7, and we get:

$-14x-21=-7(2x+3)$

we have found an equivalent to $-14x-21$  which contains $2x+3$ and since we know that $m=2x+3$:

$-14x-21=-7m$

and we substitute this into the equation

$m^2-14x-21=-6m$

$m^2-7m=-6m$

this equation is now what we anted, the original expression  in terms of m. you can represent the result like this:

$m^2-7m+6m=0\\m^2-m=0$

or what is the same: $m^2=m$