factorising all types - maths...
TRANSCRIPT
FACTORISINGALL TYPES
Junior Cert Revision
Factorise 𝑛2 − 11𝑛 + 18.
2017 JCHL Paper 1 – Question 12 (a)
𝑛2 − 11𝑛 + 18
𝑛 − 9 𝑛 − 2
Factorise fully 𝑤𝑦 − 𝑦 − 1 +𝑤.
2017 JCHL Paper 1 – Question 12 (b)
𝑤𝑦 − 𝑦 − 1 + 𝑤
= 𝑤𝑦 − 𝑦 + 𝑤 − 1
= 𝑦 𝑤 − 1 + 1 𝑤 − 1
= 𝑦 + 1 𝑤 − 1
Factorise by Grouping
Quadratic
𝑛2 − 11𝑛 + 18
𝑛 − 9 𝑛 − 2
189 26 318 1
−9𝑛
−2𝑛
−2𝑛−9𝑛−11𝑛
Use factorisation to simplify 4𝑒2 − 9
2𝑒2 + 3𝑒 − 9.
2017 JCHL Paper 1 – Question 12 (d)
4𝑒2 − 9
2𝑒2 + 3𝑒 − 9
=2𝑒 + 3 2𝑒 − 3
2𝑒 − 3 𝑒 + 3
=2𝑒 + 3
𝑒 + 3
Difference of two squares.
Quadratic
Combination Factorising –Factorise the top and bottom.
Factorise each of the following expressions.
2016 JCHL Paper 1 – Question 11 (b)
(i)25𝑥2 − 49𝑛2
(ii)2𝑥2 − 9𝑥 − 18
25𝑥2 − 49𝑛2
= 5𝑥 + 7𝑛 5𝑥 − 7𝑛
2𝑥2 − 9𝑥 − 18= 2𝑥 + 3 𝑥 − 6
Quadratic
Difference of two squares.
Factorise fully 𝑎𝑐 − 𝑎𝑑 − 𝑏𝑑 + 𝑏𝑐.
(b)
𝑎𝑐 − 𝑎𝑑 − 𝑏𝑑 + 𝑏𝑐= 𝑎𝑐 − 𝑎𝑑 + 𝑏𝑐 − 𝑏𝑑= 𝑎 𝑐 − 𝑑 + 𝑏 𝑐 − 𝑑= 𝑎 + 𝑏 𝑐 − 𝑑
Factorise by Grouping
Factorise 𝑥2 + 7𝑥 − 30.
2015 JCHL Paper 1 – Question 9 (a) (i)
𝑥2 + 7𝑥 − 30= 𝑥 + 10 𝑥 − 3
Quadratic
Factorise 𝑛2 − 1.
2015 JCHL Paper 1 – Question 12 (a) (i)
𝑛2 − 1= 𝑛 + 1 𝑛 − 1
Difference of two squares.
9𝑥2 − 16𝑦2
= 3𝑥 2 − 4𝑦 2
= 3𝑥 + 4𝑦 3𝑥 − 4𝑦
9𝑎2 − 6𝑎𝑏 + 12𝑎𝑐 − 8𝑏𝑐= 3𝑎 3𝑎 − 2𝑏 + 4𝑐 3𝑎 − 2𝑏= 3𝑎 + 4𝑐 3𝑎 − 2𝑏
Factorise fully 9𝑎2 − 6𝑎𝑏 + 12𝑎𝑐 − 8𝑏𝑐
2014 JCHL Paper 1 – Question 4 (a)
Factorise 9𝑥2 − 16𝑦2
2014 JCHL Paper 1 – Question 4 (b)
Difference of two squares.
Factorise by Grouping
2𝑥2 + 4𝑥
2𝑥2 + 𝑥 − 6
=2𝑥 𝑥 + 2
2𝑥 − 3 𝑥 + 2
=2𝑥
2𝑥 − 3
Use factors to simplify the following
2𝑥2 + 4𝑥
2𝑥2 + 𝑥 − 6
2014 JCHL Paper 1 – Question 4 (c)
Common Factor
Quadratic
Combination Factorising –Factorise the top and bottom.
Factorise each of the following expressions:
2012 JCHL Paper 1 – Question 11
(i)5𝑥3 − 10𝑥2
(ii)4𝑥2 − 81𝑦2
Common Factor
(iii)𝑎2 − 𝑎𝑏 + 3𝑎 − 3𝑏
5𝑥3 − 10𝑥2
= 5𝑥2 𝑥 − 2
4𝑥2 − 81𝑦2
= 2𝑥 + 9𝑦 2𝑥 − 9𝑦
𝑎2 − 𝑎𝑏 + 3𝑎 − 3𝑏= 𝑎 𝑎 − 𝑏 + 3 𝑎 − 𝑏= 𝑎 + 3 𝑎 − 𝑏
Difference of two squares.
Factorise by Grouping
FACTORISINGOLD COURSE
Junior Cert Revision
Factorise 8𝑥2 − 12𝑥.
2013 JCHL Paper 1 – Question 4 (b) (i)
Factorise 4𝑥2 − 12𝑥 + 9.
2013 JCHL Paper 1 – Question 4 (b) (ii)
Simplify 8𝑥2 − 12𝑥
4𝑥2 − 12𝑥 + 9.
2013 JCHL Paper 1 – Question 4 (b) (iii)
8𝑥2 − 12𝑥= 4𝑥 2𝑥 − 3
4𝑥2 − 12𝑥 + 9= 2𝑥 − 3 2𝑥 − 3
8𝑥2 − 12𝑥
4𝑥2 − 12𝑥 + 9
=4𝑥 2𝑥 − 3
2𝑥 − 3 2𝑥 − 3
=4𝑥
2𝑥 − 3
Common Factor
Quadratic
Common Factor
Quadratic
Combination Factorising –Factorise the top and bottom.
6𝑥2 − 17𝑥 + 12
3𝑥 − 4
=3𝑥 − 4 2𝑥 − 3
3𝑥 − 4= 2𝑥 − 3
4𝑐2 − 3𝑑 − 2𝑐𝑑 + 6𝑐= 4𝑐2 − 2𝑐𝑑 + 6𝑐 − 3𝑑= 2𝑐 2𝑐 − 𝑑 + 3 2𝑐 − 𝑑= 2𝑐 + 3 2𝑐 − 𝑑
Simplify 6𝑥2 − 17𝑥 + 12
3𝑥 − 4.
2012 JCHL Paper 1 – Question 3 (b) (i)
Factorise 4𝑐2 − 3𝑑 − 2𝑐𝑑 + 6𝑐.
2012 JCHL Paper 1 – Question 3 (b) (ii)
Quadratic
Combination Factorising –Factorise the top and bottom.
Factorise by GroupingRearrange 1st.
𝑥2 − 1= 𝑥 + 1 𝑥 − 1
𝑎𝑥 − 3 − 𝑎 + 3𝑥= 𝑎𝑥 − 𝑎 + 3𝑥 − 3= 𝑎 𝑥 − 1 + 3 𝑥 − 1= 𝑎 + 3 𝑥 − 1
= 6𝑥2 + 𝑥 − 35= 3𝑥 − 7 2𝑥 + 5
Factorise 𝑥2 − 1.
2011 JCHL Paper 1 – Question 4 (b) (i)
Factorise fully 𝑎𝑥 − 3 − 𝑎 + 3𝑥.
2011 JCHL Paper 1 – Question 4 (b) (ii)
Factorise 6𝑥2 + 𝑥 − 35.
2011 JCHL Paper 1 – Question 4 (b) (iii)
Factorise by GroupingRearrange 1st.
Quadratic
Difference of two squares.
Use factors to simplify 3𝑥2 − 19𝑥 − 14
𝑥2 − 49.
2010 JCHL Paper 1 – Question 5 (b) (ii)
3𝑥2 − 19𝑥 − 14
𝑥2 − 49
=3𝑥 + 2 𝑥 − 7
𝑥 + 7 𝑥 − 7
=3𝑥 + 2
𝑥 + 7
Difference of two squares
Quadratic
Combination Factorising –Factorise the top and bottom.
Factorise 25𝑥2 − 36𝑦2.
2009 JCHL Paper 1 – Question 6 (b)(i)
Factorise 11𝑥2 + 75𝑥 − 14.
2009 JCHL Paper 1 – Question 6 (b)(ii)
Simplify 3 − 4𝑥 2 − 3 − 5𝑥 2
2009 JCHL Paper 1 – Question 6 (b)(iii)
25𝑥2 − 36𝑦2
= 5𝑥 + 6𝑦 5𝑥 − 6𝑦Difference of two squares.
11𝑥2 + 75𝑥 − 14= 11𝑥 − 2 𝑥 + 7
Quadratic
3 − 4𝑥 2 − 3 − 5𝑥 2
= 3 − 4𝑥 + 3 − 5𝑥 3 − 4𝑥 − 3 − 5𝑥
= 3 − 4𝑥 + 3 − 5𝑥 3 − 4𝑥 − 3 + 5𝑥= 6 − 9𝑥 𝑥= 6𝑥 − 9𝑥2
Difference of two squares.
Simplify 3 − 4𝑥 2 − 3 − 5𝑥 2
2009 JCHL Paper 1 – Question 6 (b)(iii)
3 − 4𝑥 2 − 3 − 5𝑥 2
= 3 3 − 4𝑥 − 4𝑥 3 − 4𝑥 − 3 3 − 5𝑥 − 5𝑥 3 − 5𝑥
= 9 − 12𝑥 − 12𝑥 + 16𝑥2 − 9 − 15𝑥 − 15𝑥 + 25𝑥2
= 9 − 24𝑥 + 16𝑥2 − 9 − 30𝑥 + 25𝑥2
= 9 − 24𝑥 + 16𝑥2 − 9 + 30𝑥 − 25𝑥2
= 6𝑥 − 9𝑥2
Alternate Method
Factorise 6𝑐 + 12𝑏𝑑 − 8𝑑 − 9𝑏𝑐.
2007 JCHL Paper 1 – Question 4 (b) (i)
Simplify 7𝑥 − 2 7𝑥 + 2 − 5𝑦 − 2 5𝑦 + 2
and fully factorise the simplified expression.
2007 JCHL Paper 1 – Question 4 (b) (ii)
6𝑐 + 12𝑏𝑑 − 8𝑑 − 9𝑏𝑐= 6𝑐 − 9𝑏𝑐 − 8𝑑 + 12𝑏𝑑= 3𝑐 2 − 3𝑏 − 4𝑑 2 − 3𝑏= 3𝑐 − 4𝑑 2 − 3𝑏
7𝑥 − 2 7𝑥 + 2 − 5𝑦 − 2 5𝑦 + 2
= 7𝑥 2 − 22 − 5𝑦 2 − 22
= 49𝑥2 − 4 − 25𝑦2 − 4= 49𝑥2 − 4 − 25𝑦2 + 4= 49𝑥2 − 25𝑦2
= 7𝑥 + 5𝑦 7𝑥 − 5𝑦
Reverse of Difference of two squares!
Factorise by GroupingRearrange 1st.
Simplify 7𝑥 − 2 7𝑥 + 2 − 5𝑦 − 2 5𝑦 + 2
and fully factorise the simplified expression.
2007 JCHL Paper 1 – Question 4 (b) (ii)
7𝑥 − 2 7𝑥 + 2 − 5𝑦 − 2 5𝑦 + 2
= 7𝑥 7𝑥 + 2 − 2 7𝑥 + 2 − 5𝑦 5𝑦 + 2 − 2 5𝑦 + 2
= 49𝑥2 + 14𝑥 − 14𝑥 − 4 − 25𝑦2 + 10𝑦 − 10𝑦 − 4= 49𝑥2 − 4 − 25𝑦2 − 4= 49𝑥2 − 4 − 25𝑦2 + 4= 49𝑥2 − 25𝑦2
= 7𝑥 + 5𝑦 7𝑥 − 5𝑦
Alternate Method
Factorise 9𝑥2 − 16𝑦2.
2006 JCHL Paper 1 – Question 4 (b) (ii)
9𝑥2 − 16𝑦2
= 3𝑥 + 4𝑦 3𝑥 − 4𝑦Difference of two squares.
Factorise 2𝑙 − 𝑘𝑙 + 𝑘𝑚− 2𝑚.
2006 JCHL Paper 1 – Question 6 (b) (i)
Factorise 6𝑥2 − 19𝑥 + 10.
2006 JCHL Paper 1 – Question 6 (b) (ii)
Factorise 17𝑥 − 5𝑥2.
2006 JCHL Paper 1 – Question 6 (b) (iii)
2𝑙 − 𝑘𝑙 + 𝑘𝑚 − 2𝑚= 2𝑙 − 2𝑚 − 𝑘𝑙 + 𝑘𝑚= 2 𝑙 − 𝑚 − 𝑘 𝑙 − 𝑚= 2 − 𝑘 𝑙 − 𝑚
6𝑥2 − 19𝑥 + 10= 3𝑥 − 2 2𝑥 − 5
Quadratic
8𝑥2 − 12𝑥= 4𝑥 2𝑥 − 3
Common Factor
Factorise by GroupingRearrange 1st.
Factorise 3𝑥2 + 8𝑥 − 3.
2005 JCHL Paper 1 – Question 3 (b) (i)
Factorise 3𝑝 − 𝑐 + 3𝑝𝑐 − 𝑐2.
2005 JCHL Paper 1 – Question 3 (b) (ii)
Simplify 2𝑥 − 1 2 − 𝑥 − 1 2
2005 JCHL Paper 1 – Question 3 (b) (iii)
3𝑝 − 𝑐 + 3𝑝𝑐 − 𝑐2
= 3𝑝 + 3𝑝𝑐 − 𝑐 − 𝑐2
= 3𝑝 1 + 𝑐 − 𝑐 1 + 𝑐= 3𝑝 − 𝑐 1 + 𝑐
6𝑥2 − 19𝑥 + 10= 3𝑥 − 2 2𝑥 − 5
Quadratic
2𝑥 − 1 2 − 𝑥 − 1 2
= 2𝑥 − 1 + 𝑥 − 1 2𝑥 − 1 − 𝑥 − 1
= 2𝑥 − 1 + 𝑥 − 1 2𝑥 − 1 − 𝑥 + 1= 3𝑥 − 2 𝑥= 3𝑥2 − 2𝑥
Difference of two squares.
Factorise by GroupingRearrange 1st.
2𝑥 − 1 2 − 𝑥 − 1 2
= 2𝑥 2𝑥 − 1 − 1 2𝑥 − 1 − 𝑥 𝑥 − 1 − 1 𝑥 − 1
= 4𝑥2 − 2𝑥 − 2𝑥 + 1 − 𝑥2 − 𝑥 − 𝑥 + 1= 4𝑥2 − 4𝑥 + 1 − 𝑥2 − 2𝑥 + 1= 4𝑥2 − 4𝑥 + 1 − 𝑥2 + 2𝑥 − 1= 3𝑥2 − 2𝑥
Alternate Method
Simplify 2𝑥 − 1 2 − 𝑥 − 1 2
2005 JCHL Paper 1 – Question 3 (b) (iii)
Factorise 9𝑥2 − 64𝑦2.
2004 JCHL Paper 1 – Question 4 (b) (i)
Factorise 3𝑥𝑦 − 10𝑥 − 10𝑏 + 3𝑏𝑦.
2004 JCHL Paper 1 – Question 4 (b) (ii)
Factorise 6𝑥2 − 7𝑥 − 24.
2004 JCHL Paper 1 – Question 4 (b) (iii)
Quadratic
Difference of two squares. 9𝑥2 − 64𝑦2
= 3𝑥 + 8𝑦 3𝑥 − 8𝑦
3𝑥𝑦 − 10𝑥 − 10𝑏 + 3𝑏𝑦= 3𝑥𝑦 + 3𝑏𝑦 − 10𝑥 − 10𝑏= 3𝑦 𝑥 + 𝑏 − 10 𝑥 + 𝑏= 3𝑦 − 10 𝑥 + 𝑏
6𝑥2 − 7𝑥 − 24= 3𝑥 − 8 2𝑥 + 3
Factorise by GroupingRearrange 1st.
Factorise 4𝑥2 − 49.
2003 JCHL Paper 1 – Question 4 (b) (i)
Factorise 𝑎𝑏 − 𝑐𝑏 + 𝑎𝑐 − 𝑐2.
2003 JCHL Paper 1 – Question 4 (b) (ii)
Factorise by Grouping
Difference of two squares. 4𝑥2 − 49= 2𝑥 + 7 2𝑥 − 7
𝑎𝑏 − 𝑐𝑏 + 𝑎𝑐 − 𝑐2
= 𝑏 𝑎 − 𝑐 + 𝑐 𝑎 − 𝑐= 𝑏 + 𝑐 𝑎 − 𝑐
Factorise fully each of the following:
2002 JCHL Paper 1 – Question 3 (a)
(i)𝑥2 − 7𝑥 + 12
(ii)4𝑥2 − 25𝑦2
Quadratic𝑥2 − 7𝑥 + 12= 𝑥 − 4 𝑥 − 3
4𝑥2 − 25𝑦2
= 2𝑥 + 5𝑦 2𝑥 − 5𝑦Difference of two squares.
Factorise fully each of the following:
2001 JCHL Paper 1 – Question 3 (a)
(i)20𝑥𝑦 − 4𝑥2
(ii)5𝑥2 − 9𝑥 − 2
Common Factor20𝑥𝑦 − 4𝑥2
4𝑥 5𝑦 − 𝑥
5𝑥2 − 9𝑥 − 2= 5𝑥 + 1 𝑥 − 2
Quadratic