Thread: Please check my answers :) (Factoring)

Factor completely:

1. 5k³- 40

5(k-2)(k² + 2k + 4)


2. t² - 81/169

(t + 9/13)(t - 9/13)


3. 12b²+ 36b + 27

(2b+3)2


4. b⁴- 16

(b² +4)(b+2)(b-2)

82. (2k-7)h² - 4 (2k-7)h-45(2k-7)

(2k-7)(h+5)(h-9)


Thank you

Correct except that you have lost a factor of 3 in no.3 Should be 3(2b+3)^2

Originally Posted by Kibbygirl

Factor completely:

1. 5k³- 40

5(k-2)(k² + 2k + 4)

Yes, that is correct.

2. t² - 81/169

(t + 9/13)(t - 9/13)

Yes, that is correct.

3. 12b²+ 36b + 27

(2b+3)2

No, that is not correct. What you have written is the same as 2(2b+ 3)= 4b+ 6 (multiplication is commutative). What I think you meant was
(2b+ 3)² but that is still incorrect. (2b+ 3)²= (2b)²+ 2(2b)(3)+ 3²= 4b²+ 12b+ 9. Did you leave out a "3" that you factored out first? 12b²+36b+ 27= 3(4b²+ 12b²+ 9)= 3(2b+ 3)².

4. b⁴- 16

(b² +4)(b+2)(b-2)

Yes, this is correct.

82. (2k-7)h² - 4 (2k-7)h-45(2k-7)

(2k-7)(h+5)(h-9)

Yes, that is correct.

Thank you