Subtraction: Change Signs
Algebra Help: Section 2.7
Change signs when subtracting with algebra.
From the two examples, on the previous page subtraction with algebra, we learned that a positive term is subtracted by changing its sign to a minus. A negative term is subtracted by changing its sign to a plus.
For example two negatives or two subtractions equal a positive.
As in English, a man did not not drive to the store
,
means a man drove to the store
.
+16 minus -2 = +16 plus 2 = 18 +16 minus -2 = +16 + 2 = 18
This principle is further illustrated by the following example. Change the sign of the positive numbers to negative. Change the sign of the negative numbers to positive. To obtain the correct result, as reading from left to right, the implied positive signs of 4 and 2 must change to -. The signs of -2 and -4 must change to +.
3. OPERATION
From 16 16 16 16 16
Subtract 4 2 0 -2 -4
___________________
Remainder 12 14 16 18 20
4. From +7a subtract +12a.
OPERATION
Minuend +7aSubtrahend -12a_____ Difference -5a
ANALYSIS - We change the sign of the subtrahend as in the other examples; then
the sum of -12a and +7a is -5a, the algebraic difference.
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Help with Algebra Homework
Free tutorials provide math help for math problems. Tutorials start with algebra 1. Algebra tutorials include word problems related to algebra topics, as they're introduced. See the menu, above for algebra math equations, and explanation, by section.
Windows algebra games, designed to help with classwork, coming soon!
Windows games, in progress, work with this set of free tutorials, modified
from the public domain text book titled,
New Elementary Algebra
containing the rudiments of the science for schools and academies.
By Horation N Robinison, LL. D. Ivison, Blakeman & Company, Publishers, New York and Chicago.
