Grade 8 MATH Factoring

10/28/15
Activity 19: Spotting errors
Description: This activity will check how well you apply your factoring skills.
Direction: Spot the errors on the factoring problems below:

• Is x2-4x-12 = 12-4x-x2?
• x2-4x-12 = 12-4x-x2
• x2-4x-12 = (x+2)(x+6)
• 12-4x-x2 = (x-6)(x+2)
• Apply the difference of terms in 3x2-12x
• Answer: 3x2-12x = 3x(x2-4) = (x-2)(x+2)
• Is x2+36 factorable by difference of squares?
• Answer: No, because x2-36 has missing parts, or may have been a result of another factor.
• Make a generalization for errors found below:
• x2+4 = Not factorable
• 2.6x2-9 = Not factorable
• 4x2y5 - 12x3y6 + 2y2 = Not factorable
• Conclusion: All polynomials above cannot be factored.

Activity 20: IRF Revisited

Initial Revised Final    
  

Initial		Revised		Final
		(2x+3)(2x-4)		(2x+3)(2x-4)
	9m2 – 16m2		9m2 – 16m2		(3m-4n)(4m+4n)
			(2x-3)(2x+3)		(2x-3)(2x+3)
	27x3 – 8y2		27x3 – 8y2		27x3 – 8y2
	a3+125b		a3+125b		(a+5b)(a2-5b+25b2)

   

Activity 21: 2=1 is possible to me!
How can 2=1 be possible?
Answer:

• a2=b2
• a2-b2 = b(a-b)
• (b)(b) = 2b
• 2b/b = 1
• 2 = 1!

Activity 22: Journal writing

Description: Reflect your lesson by completing the sentences

• ·         I learned that… Factoring is putting special products into question form.
• ·         I’m surprised that… Factoring is the reversed of special products
• ·         I noticed that… Factoring had many methods to be solved.
• ·         I discovered that… All factoring methods lead back to the basic method of factoring.