Subtracting Polynomials

To subtract a polynomial in parentheses, subtract each of its terms. In 4x^2 + x - (x^2 - 3x), the minus sign applies to both x^2 and -3x. Subtracting x^2 gives -x^2. Subtracting -3x is the same as adding 3x. So the expression becomes 4x^2 + x - x^2 + 3x.

When you remove parentheses with a minus sign in front, change the sign of every term inside. So - (x^2 - 3x) becomes - x^2 + 3x. Then collect the like terms. The squared terms give 4x^2 - x^2 = 3x^2, and the x terms give x + 3x = 4x. The result is 3x^2 + 4x.

Subtracting -3x is the same as adding 3x, because two minus signs make a plus. When you remove parentheses with a minus sign in front, change the sign of every term inside, not only the first one.