Video Transcript
Given that five plus 𝑛 equals
negative five, find the value of 𝑛.
We have the equation five plus 𝑛
equals negative five. This is telling us that when we add
some value to five, the result is negative five. To find out what 𝑛 is, we need to
think about the inverse property of addition. The inverse property of addition
says that any number added to its opposite will equal zero. Since five and 𝑛 are being added
together, if we subtract five, then five minus five will equal zero. But we also know the subtraction
property of equality, which tells us that if we subtract five from one side of the
equation, we must subtract five from the other side of the equation to keep it
balanced. If five minus five is zero, then on
the left side of the equal sign, we only have the variable 𝑛. And on the right side, we have
negative five minus five, which equals negative 10. And so, we found that 𝑛 equals
negative 10.
If you start with five and add
negative 10 to that five, you’ll get negative five. This is a vertical method for
solving the problem. We do this by writing the next line
directly under the line above it. The other way to do it would be to
use a horizontal method. We began with five plus 𝑛 equals
negative five. But then, in the next line, we’ll
add the negative five in the row with our original equation. So that it says five minus five
plus 𝑛 equals negative five minus five. Both methods show that 𝑛 is equal
to negative 10.
