Identify GCF: First, identify the greatest common factor (GCF) of the terms in the polynomial 21x+18x2−3x3. The GCF of 21x, 18x2, and −3x3 is 3x.
Factor out GCF: Factor out the GCF from each term in the polynomial. 3x(7+6x−x2)
Rearrange terms: Rearrange the terms inside the parentheses in descending order of the powers of x.3x(−x2+6x+7)
Factor quadratic expression: Now, factor the quadratic expression inside the parentheses.To factor −x2+6x+7, we look for two numbers that multiply to −7 (the product of the coefficient of x2 and the constant term) and add up to 6 (the coefficient of x).The numbers that satisfy these conditions are 7 and −1.
Write factored form: Write the factored form of the quadratic expression using the two numbers found in the previous step. 3x(−(x−7)(x+1))
Factor out negative sign: Since there is a negative sign in front of the quadratic, we can factor out −1 to simplify the expression.3x(−1)(x−7)(x+1)
Combine constants: Combine the constants to get the final factored form.−3x(x−7)(x+1)
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