Now subtracting polynomials is much the same as adding them, you just need to pay very close attention to all negative signs.
Remember, if you are asked to subtract a whole quantity, you must subtract every element inside the quantity.
EX:
(7x + 4) - (2x +9) means you must subtract
the 2x AND also the 9.
.......7x
+ 4 - 2x - 9 we can remove the parentheses when we write the
subtraction of each element in the quantity.
If we rewrite this as an addition problem using the definition of subtraction as addition of the opposite wherever we see a subtraction sign, then we can use the commutative and associative properties of addition to rearrange and put like terms together......WATCH!
7x
+ 4 + -2x + -9 .......rewriting
all subtractions as addition of the opposite
7x + -2x + 4 + -9........rearrange
using the commutative property of addition
(7x + -2x) + (4 + -9)....use
the associative property of addition to group like terms
5x + -5 is the answer
*JUST A QUICK REMINDER! remember that the coefficient, or number in front of, -x is (-1).
Now you try a few: click the answer links to see if you are right
- (3x + 12) - (5x - 6) = ? answer
- (-4x^2 - 3x) - (-5x^2 + 7x) = ? answer
- (4x^2y - 3xy^2) - (3x^2y - 9xy^2) = ? answer
