Warm up Factor the expression. 1. 2x2 + 6x + 4 2. 3x2 + 2x – 1 3. 5x2 – 500
Solving Polynomial Equations 5.5 Solving Polynomial Equations
Sum and Difference of cubes (a3 + b3) = (a + b)(a2 – ab + b2) (a3 – b3) = (a – b)(a2 + ab + b2)
Perfect Cubes 1 8 27 64 125 216 343 512 729 1000
Example 1: Factor the expression. a) x3 +125 b) 8y3 – 27
What’s the first thing we do when we factor? Take out the GCF! Example 2: Factor the expression. a) 64h4 – 27h b) x3 y + 343y
Factor by Grouping 1. Divide the terms in a polynomial into two groups. 2. Take out a GCF from each group, so the remaining factors are the same. 3. Take out the new GCF. 4. Factor the factors if possible.
Example 3 : Factor the expression. a) 2x3 – 3x2 – 10x + 15
Example 3: Factor the expression. b) x2 y2 – 3x2 – 4y2 + 12
Example 3: Factor the expression. c) bx2 + 2a + 2b + ax2
Quadratic Form Example: x6 + x3 – 2 = (x3)2 + x3 – 2
Quadratic Form Example 4: x4 – 6x2 – 27 b) 25x4 – 36 It is like factoring a quadratic – just not second degree. Example 4: x4 – 6x2 – 27 b) 25x4 – 36 c) 4x6 – 20x3 + 24
Solve polynomials by factoring Put the polynomials in standard form Factor as far as you can – starting with the GCF Set all the factors with variables equal to zero Solve these new equations You should have as many solutions as the degree of the polynomial.
Example 5: Solve. x2 + 2x = 0
Example 6: Solve. 54x3 – 2 = 0
Example 7: Solve. x 4 – 29x 2 + 100 = 0
Example 8: Solve. a) 3x3 + 7x2 = 12x b) x3– 18 = - 2x2 + 9x