How to subtract trinomials

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PSAT Math › How to subtract trinomials

Questions 1 - 3

1

Subtract:

Explanation

When subtracting trinomials, first distribute the negative sign to the expression being subtracted, and then remove the parentheses:

Next, identify and group the like terms in order to combine them: .

2

Find the difference:

Explanation

Find the difference:

Distribute the negative to the second trinomial:

Combine like terms:

3

Evaluate the following:

$(2x^2+\frac{3}{4}x-5) - (x^2+x-10)$

$x^2-\frac{1}{4}x + 5$

$x^2-\frac{7}{4}x + 10$

$3x^2-\frac{1}{4}x + 5$

$x^2-\frac{1}{4}x -15$

Explanation

To subtract these two trinomials, you first need to flip the sign on every term in the second trinomial, since it is being subtrated:

$(2x^2+\frac{3}{4}x-5) - (x^2+x-10)$

$2x^2+\frac{3}{4}x-5 - x^2-x+10$

Next you can combine like terms. You have two terms with , two terms with , and two terms with no variable:

$x^2-\frac{1}{4}x+5$

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