whollymoses
Hi all,
I am in the middle of a
TTP question and seem to be getting stuck on particular step.
Original question stem for context
If \(x-5 = \frac{2}{3}(y-5)\), and \(x+10=\frac{5}{6}(y+10)\), what is the value of xy?
First step: [Equation one] eliminate the fraction by multiplying the entire equation by 3.
TTP says:
\(3(x-5=\frac{2}{3}(y-5))\)
\(3x-15=2(y-5)\)
\(3x-15=2y-10\)
\(3x=2y+5\)
But why don't you multiply the \((y-5) \) by 3 as well?
I was doing this:
\(3(x-5=\frac{2}{3}(y-5))\)
\(3x-15=2(3y-15)\)
\(3x-15=6y-30\)
\(3x=6y-15\)
\(x=2y-5\)
Hi whollymoses,
Remember, when you multiply a number through an equation you can multiply each term JUST ONCE.
So, in this case, you should see that 2/3(y - 5) is just one term.
So when you multiply the entire equation by 3, we only need to multiply 2/3 by 3 and not the rest of the parenthesis. If you were to do that you’d be changing the value of the equation.