Q. Factor the following expression completely.x4+3x3+2x2−9x2−27x−18Answer:
Identify and group terms: Identify and group terms that can be combined in the polynomial. x4+3x3+2x2−9x2−27x−18 can be rewritten by combining like terms (2x2−9x2). This gives us x4+3x3−7x2−27x−18.
Look for common factors: Look for common factors in all terms.There are no common factors in all terms of the polynomial x4+3x3−7x2−27x−18.
Group terms for factoring: Group terms to facilitate factoring by grouping. Group the terms as follows: (x4+3x3)+(−7x2−27x)−18.
Factor by grouping: Factor by grouping.First group: x4+3x3 can be factored as x3(x+3).Second group: −7x2−27x can be factored as −x(7x+27).The expression becomes x3(x+3)−x(7x+27)−18.
Notice common factor: Notice that the first and second groups have a common factor of x+3. Rewrite the expression to make this common factor more apparent. The expression becomes x3(x+3)−9x(x+3)−18.
Factor out common factor: Factor out the common factor of x+3. The expression becomes (x+3)(x3−9x)−18.
Factor further: Notice that x3−9x can be factored further.x3−9x is a difference of cubes since 9x=32×x and can be written as x(x2−9).Factor x2−9 as a difference of squares: x(x−3)(x+3).The expression becomes (x+3)(x(x−3)(x+3))−18.
Distribute x inside parentheses: Distribute the x inside the parentheses.The expression becomes (x+3)(x2(x−3)+3(x−3))−18.
Factor out common factor: Factor out the common factor of (x−3) from the terms inside the parentheses.The expression becomes (x+3)((x2+3)(x−3))−18.
Distribute across: Distribute the (x+3) across the (x2+3)(x−3). The expression becomes (x+3)(x2+3)(x−3)−18.
Check for additional factor: Now, we need to see if −18 can be factored with the rest of the expression.Since there is no x term with −18, it cannot be factored with the rest of the expression.The final factored form of the expression is (x+3)(x2+3)(x−3)−18.
More problems from Operations with rational exponents