Addition and Subtraction of Polynomials
Addition of Polynomials
To add two polynomials, combine their like
terms.
Example 1: (4x5 + x4 -12x3 + x - 6) + (3x4 +8x3 +6x2 - x) =?
= 4x5 + (1 + 3)x4 + (- 12 + 8)x3 +6x2 + (- 1 + 1)x - 6
= 4x5 +4x4 -4x3 +6x2 + 0x - 6
= 4x5 +4x4 -4x3 +6x2 - 6
Example 2: (- 3x4 -2x2 + x + 17) + (14x6 +12x5 -2x4 +7x3 +2x2 - 4x - 12) =?
= 14x6 +12x5 + (- 3 - 2)x4 +7x3 + (- 2 + 2)x2 + (1 - 4)x + (17 - 12)
= 14x6 +12x5 -5x4 +7x3 +0x2 - 3x + 5
= 14x6 +12x5 -5x4 +7x3 - 3x + 5
Subtraction of Polynomials
To subtract one polynomial from another, change the subtraction sign to an addition sign
and change the signs of all the terms in the polynomial being subtracted (don't
forget to change the sign of the first term). Then add the resulting polynomial by
combining like terms.
Example 3: (3x4 +4x3 -5x2 +18) - (7x5 +3x4 -12x3 -3x2 + 7x - 9) =?
= (3x4 +4x3 -5x2 +18) + (- 7x5 -3x4 +12x3 +3x2 - 7x + 9)
= - 7x5 + (3 - 3)x4 + (4 + 12)x3 + (- 5 + 3)x2 - 7x + (18 + 9)
= - 7x5 +16x3 -2x2 - 7x + 27
Example 4: (- 5x6 -3x4 +18x3 -7x2 +9x + 11) - (- x4 + x3 -12x2 + 10x + 5) =?
= (- 5x6 -3x4 +18x3 -7x2 +9x + 11) + (x4 - x3 +12x2 - 10x - 5)
= - 5x6 + (- 3 + 1)x4 + (18 - 1)x3 + (- 7 + 12)x2 + (9 - 10)x + (11 - 5)
= - 5x6 -2x4 +17x3 +5x2 - x + 6
