MATHEMATICS
PAPER ONE(P1)
GRADE 12 
EXAM PAPERS AND MEMOS
SEPTEMBER 2016

NOTE:

  • If a candidate answered a question TWICE, mark the FIRST attempt ONLY.
  • Consistent accuracy applies in ALL aspects of the memorandum.
  • If a candidate crossed out an attempt of a question and did not redo the question, mark the crossed-out attempt.
  • The mark for substitution is awarded for substitution into the correct formula.

MEMORANDUM

QUESTION 1

1.1.1

𝑥− 4𝑥−12=0
(𝑥 − 6)(𝑥 + 2)=0
𝑥 = 6 or 𝑥 = −2

✔ standard form
✔ 𝑥=6 (CA applies)
✔ 𝑥=−2 (CA applies)

(3)

     

1.1.2

3𝑥2+2𝑥−6=0
𝑥=−(2) ± √(2)− 4(3)(−6)
                2(3)
𝑥=−2 ± √766
𝑥=−1,79 or 𝑥=1,12

 Penalise 1 mark for incorrect rounding off.

✔ substitution

✔ x = −1,79 

✔ x = 1,12 

(3)

     

1.1.3 

 3𝑥− 1 = 27-x
                 3
3𝑥− 1 = 3−3𝑥 −1
∴ 𝑥− 1=−3𝑥 − 1
𝑥+ 3𝑥 = 0
𝑥 (𝑥+3) = 0
𝑥 = 0 or  𝑥 = −3

OR

3𝑥− 1 = 27 − 𝑥3
3𝑥− 1.3 = 27−𝑥
3𝑥−1 + 1 = 3−3𝑥
∴ 𝑥2=−3𝑥
𝑥+ 3𝑥 = 0
𝑥(𝑥+3) = 0
𝑥=0 or 𝑥=−3

✔ 3−3𝑥−1 
✔ equating exponents
✔factors/faktore 
✔ both x-values

 

 

 

✔𝑥−1 + 1 = 3−3𝑥
✔equating exponents 
✔ factors/faktore 
✔both x-values

(4)

1.2.1 1 +1/𝑥 = 0
𝑥 + 1 = 0
   𝑥 
𝑥 =−1 or  𝑥=0

✔ 𝑥 =−1
✔ 𝑥=0

(2)

     
1.2.2 𝑥−1/𝑥  =1
1+1/𝑥
𝑥 −1/𝑥=1 +1/𝑥
𝑥− 1 = 𝑥 + 1
𝑥− 𝑥 − 2 = 0
(𝑥+1)(𝑥−2) = 0
𝑥=−1 or 𝑥=2
𝑥=2 only

✔ manipulation of equation 
 ✔ standard form
✔ factors
✔ both x-values
✔ choosing x = 2 

(5) 
[17]

QUESTION 2   
2.1

𝑥 − 𝑦 =3 ; 𝑥𝑦 = 28
𝑥 − 𝑦 = 3…………………..(1)
𝑥𝑦 = 28………………… (2)
From (1) 𝑥 = 𝑦 + 3
Substitute in (2)
𝑦(𝑦+3) = 28
𝑦+ 3𝑦 − 28 = 0
(𝑦−4)(𝑦+7)  =0
𝑦=4 or  𝑦=−7
𝑥=7 or  𝑥=−4

OR

From  (1) 𝑦 = 𝑥−3
Substitute in (2)
𝑥(𝑥−3) = 28
𝑥− 3𝑥 − 28 = 0
(𝑥+4)(𝑥−7) = 0
𝑥=−4 or  𝑥=7
𝑦=−7 or  𝑦=4

✔ 𝑥 = 𝑦 + 3
✔ substitute in (2)
✔ standard form
✔ factors
✔ y-value
✔ x-values

 

 

✔ 𝑦 = 𝑥 − 3✔ substitute in (2)
✔ standard form
✔factors
✔ x-values
✔ y-values

(6)

     
2.2 𝑥2  ≤ 4 + 3𝑥 ; 𝑥 > 0
𝑥− 3𝑥 − 4 ≤ 0 
(𝑥+1)(𝑥−4) ≤ 0
you
Solution −1 ≤ 𝑥 ≤4
But 𝑥 >0
0 < 𝑥 ≤ 4

✔ standard form/standaardvorm
✔ factors/faktore 
✔ solution/oplossing  
−1 ≤ 𝑥 ≤4
✔ final answer/finale antwoord 
0 < 𝑥 ≤ 4

(4) 
[10]

QUESTION 3   
3.1 wow

𝑇𝑛 = 𝑎𝑛+ 𝑏𝑛 + 𝑐
2𝑎 = 2
𝑎 =1
3𝑎 + 𝑏 = 2
3 + 𝑏 = 2
𝑏 = −1
𝑎 + 𝑏 + 𝑐 = 1 
1 − 1 + 𝑐 =1
𝑐 =1
𝑇𝑛 = 𝑛− 𝑛 + 1
Row 80 Term 1
𝑇80 = 80− 80 + 1
𝑇80 = 6321

✔ a = 1 
✔ b = −1 
✔ c = 1 
✔ 𝑇𝑛 = 𝑛− 𝑛 + 1
✔ 6321 

(5)

     
3.2

Row 80
6321 6323 6325 6327 ...
𝑆𝑛=𝑛/2[2(𝑎) + (𝑛 − 1)𝑑]
𝑆80 80/2 [2(6321)+(80−1)(2)] Row 80
𝑆80 = 512000

OR

Row 80 Term 80
𝑇80 = 6321 + (79×2)
𝑇80 = 6479
𝑆𝑛 = 𝑛2[𝑎 + 𝑙]
𝑆80 = 80/2[6321 + 6479] Row 80
𝑆80 = 512000

OR

TO THE EG
2𝑎 = 2
𝑎 = 1
3𝑎 + 𝑏 = 4
3 + 𝑏 = 4
𝑏 = 1
𝑎  + 𝑏 + 𝑐 = 1
1 + 1 + 𝑐 = 1
𝑐 = −1

𝑇𝑛 = 𝑛+ 𝑛 − 1
𝑇𝑛 = 𝑛2+ 𝑛 − 1
𝑇80 = 80+ 80 −1
𝑇80 = 6479
𝑆𝑛= 𝑛/2[𝑎+𝑙]
𝑆80=80/2[6321+6479] Row 80
𝑆80=512000

✔ n= 80 
✔ d = 2 
✔ sub into correct formula   
✔ answer(4) 

 

 

 

✔ calculating term 80 of row  
✔ 6479 
✔ sub into correct formula 
✔ answer (4)

 

 

 

 

 

 

 

 

✔ 𝑇𝑛 = 𝑛+ 𝑛 − 1
✔ 𝑇80 = 6479
✔ sub into formula
✔ answer 

(4) 
[9]

QUESTION 4   
4.1.1   𝑇10 = 𝑆10 − 𝑆9
𝑇10 = 10(11)(12) − 9(10)(11)
𝑇10 = 330
 ✔ setting up of equation

✔ substitution
✔ answer

(3)

     
4.1.2

𝑝 ;3𝑝 ;5𝑝 ;……………
𝑑 = 2𝑝
𝑆𝑛=𝑛/2[2𝑎 + (𝑛 − 1)𝑑]
𝑆𝑝=𝑝/2[2𝑝 + (𝑝 − 1)2𝑝]
𝑆𝑝=𝑝/2(2𝑝 + 2𝑝2−2𝑝)
𝑆𝑝=𝑝3

OR


𝑎 = 𝑝
𝑙 = 2𝑝− 𝑝
𝑆𝑛 = 𝑛/[𝑎 + 𝑙]
𝑆𝑝=𝑝/2[𝑝+2𝑝− 𝑝]
𝑆𝑝=𝑝3

✔ first three terms
✔ 𝑑 = 2𝑝
✔ substitution
✔ answer (4) 

 

 

 

✔ 𝑎 = 𝑝
✔ 𝑙 = 2𝑝− 𝑝
✔ substitution
✔ answer 

(4) 
[7]

  QUESTION 5 
5.1

𝑟 = 𝑥+2
       𝑥
𝑇3 = (𝑥+2)2
           𝑥

Answer Only 2/2 

✔ ratio
✔ answer

(2)

     
5.2

𝑆∞=  𝑎  
     1−𝑟
−8=       𝑥       
        1 − (𝑥+2)/𝑥
−8=     𝑥          
        𝑥−𝑥−2
𝑥2=16
𝑥  = ±4

- 1 MARK FOR (±) 
✔ substitution
✔ simplification
✔ 𝑥2=16

✔ both answers 

(4) 
[6]

QUESTION 6   
6.1 𝐴 = 𝑃(1−𝑖)𝑛
𝐴 = 635000(1−15/100)5
𝐴 = 281 752,87

✔ 𝑖=15/100 and 𝑛 =5
✔ sub into correct formula
✔ answer

(3)

     
6.2.1 𝑃𝑣 = 𝑥[1 − (1+𝑖)−𝑛]
                𝑖
50000 = 𝑥[1− (1 + 16.75/1200)−48]      
                       16.75/1200
𝑥 = 𝑅 1 436,29

✔ 𝑖=16.75/1200
✔ 𝑛=−48
✔ sub into correct formula
✔ answer

(4)

     
6.2.2

𝑃𝑣 = 𝑥[1 − (1+𝑖)−𝑛]
                𝑖
𝑃𝑣 = 1436.29 [1 − (1+16.75/1200)−18]
                          16.75/1200
𝑃𝑣 = 𝑅22 721,97704
𝑃𝑣 = 𝑅22 722

OR

Outstanding balance (OB)
OB = 50000(1+ 16.75/1200)30[1436.29 [(1 + 16.75/1200)30−1]]
                                                                     16.75/1200
OB =  𝑅 22722,14
OB = 𝑅22722

✔ 𝑛=−18
✔ 𝑖=16.75/1200
✔ substitution
✔ answer
✔ rounding

(5)

✔ 𝑛=30
✔ 𝑖=16.75/1200
✔ sub into both formulae
✔ answer
✔ rounding

(5)

     
 6.3  𝐴 = 𝑃(1+𝑖)𝑛
𝐴 = 2𝑥 and 𝑃 = 𝑥
2𝑥 = 𝑥(1+14.75/100)𝑛
𝑛 =        log2            
       log(1 +14.75/100)
𝑛 = 5.04 𝑦𝑒𝑎𝑟𝑠

✔ 𝐴 = 2𝑥 and 𝑃 = 𝑥
✔ sub into correct formula
✔ using of logs
✔ answer

(4)
[16]

QUESTION 7
7.1.1 x = 0

✔answer 

(1)

     
7.1.2 x > -2 ; x # 0

✔x > -2
✔x # 0

(2)

     
7.1.3 y = -4

✔answer 

(1)

     
7.1.4 𝑦 = 𝑏𝑥 − 4
5 = 𝑏− 4
𝑏= 9
𝑏 = ±3
𝑦 = 3𝑥−4

✔ sub of −4
✔ sub of point (2;5)
✔ 𝑏 = ±3
✔ answer with correct 𝑏 value

(4)

     
7.1.5 x = -2
y = -1

✔x = -2
✔y = -1

(2)

     
7.1.6 𝑦 =    𝑎     −1
      𝑥+2
−3 =   𝑎    − 1
        0+2
𝑎=−4
𝑦=  −4   − 1
     𝑥+2

✔ sub of asymptotes
✔ sub of point (0;-3)
✔ 𝑎=−4

(3)

     
7.1.7 𝑦 = 𝑥 + 2 −1
𝒚 = 𝒙 + 𝟏
𝑦 = −(𝑥 + 2) −1
𝒚 = −𝒙 − 𝟑

✔𝒚 = 𝒙 + 𝟏
✔𝑦 = −(𝑥 + 2) −1
✔𝒚 = −𝒙 − 𝟑

(3)

     
 7.2.1  𝑦 = log½𝑥
𝑓−1 ∶ 𝑥= log½𝑦
𝑦 = (½)𝑥
OR
𝑦 = 2−𝑥

✔swopping of x and y
✔answer

(2)

     
7.2.2 7.2.2

✔Shape 
✔y-intercept
✔any other correct point

(3)

     
7.2.3

g(x) = (½)-x

OR

g(x) = 2x

✔✔Answer

✔✔Answer

(2)

     
7.2.4 x > 1

✔✔x > 1

(2)
[25]

QUESTION 8
8.1 x = -3

✔x = -3

(1)

     
 8.2  𝑦 = 𝑎(𝑥 + 3)− 5
4 = 𝑎(9) − 5
9𝑎 = 9
𝑎 = 1
𝑦 = 𝑥+ 6𝑥  + 9 − 5
𝑦=𝑥+ 6𝑥 + 4
𝑎 = 1 and 𝑏 = 6

✔ sub of turning point
(−3;5)
✔ sub of (0;4)
✔ simplification

(3)

     
8.3 Δ = 𝑏− 4𝑎𝑐
Δ = 36 − 4(1)(4)
Δ=20
𝑅𝑜𝑜𝑡𝑠 𝑎𝑟𝑒 𝐼𝑟𝑟𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑎𝑛𝑑 𝑈𝑛𝑒𝑞𝑢𝑎𝑙

✔ Δ=20
✔ irrational
✔ unequal

(3)

     
8.4

𝑔(𝑥) = 2𝑥
𝑥+ 6𝑥 + 4 = 2𝑥
𝑥+ 4𝑥 + 4 = 0
(𝑥+2)= 0
𝑥 = −2
𝑔(−2)=−4

Point (−2;−4)

OR

𝑓(𝑥) = 𝑥+ 6𝑥 + 4
𝑓′(𝑥) = 2𝑥 + 6 and 𝑚 = 2
2𝑥 + 6 = 2
2𝑥 = −4
𝑥 = −2
𝑦 = −4
Point (−2;−4)

✔ 𝑔(𝑥) = 2𝑥
✔ equating equations
✔ 𝑥 = −2
✔ 𝑦 = −4

 

✔ derivative
𝑓′(𝑥) = 2𝑥 +6
✔ equating to gradient of g.
✔ x-value
✔ y-value

(4)
[11]

QUESTION 9   
 9.1

 𝑓(𝑥) = 3𝑥− 1
𝑓′(𝑥) = lim   𝑓(𝑥+ℎ)−𝑓(𝑥)
          ℎ→0          ℎ
=    lim  3(𝑥 + ℎ)− 1 −(3𝑥− 1)
     ℎ→0                      h
=   lim  3(𝑥2 + 2xh + h2) − 1 - 3𝑥− 1
     ℎ→0                      h
=   lim  3𝑥2 + 6xh + 3h2− 1 - 3𝑥− 1
     ℎ→0                      h
=       lim     6𝑥ℎ
        ℎ→0      h
= 6𝑥

 Answer only = 0 marks

Penalise 1 mark for incorrect use of formula. Must show 𝑓′(𝑥). 

✔ formula
✔substitution of (𝑥+ℎ)
✔ simplification
3𝑥+ 6𝑥ℎ + 3ℎ− 1 − 3𝑥+ 1
✔ =  lim     6𝑥ℎ
        ℎ→0     h
✔ answer

(5)

     
 9.2.1  𝑦 = 5𝑥2 + √𝑥
𝑦 = 5𝑥+ 𝑥½
𝑑𝑦/𝑑𝑥 = 10𝑥 + ½𝑥−½

✔𝑥½
✔10x
✔½𝑥−½

(3)

     
 9.2.2  𝐷𝑥 [6𝑥−4]
         3𝑥
𝐷𝑥[6𝑥/3𝑥−4/3𝑥]
𝐷𝑥[2 − 4/3𝑥−1]
=−4/3𝑥−2 or  4/3𝑥2

✔ 2
✔ −4/3𝑥−1
✔ answer

(3)

     
9.2.3 𝑚 = 𝑠′(𝑡) =3𝑡2
𝑡2 ≥ 0
3𝑡2 ≥ 0
∴ no value of t will make 𝑠′(𝑡) negative.

✔ derivative
✔ 3𝑡≥ 0

(2)
[13]

QUSTION 10
10.1

𝑓(𝑥) = 𝑥3 − 𝑥2 − 8𝑥 + 12
(𝑥−2)(𝑥2 + 𝑥 − 6) = 0
(𝑥−2)(𝑥−2)(𝑥+3) = 0
𝑥=2 or 𝑥=2 or 𝑥 = −3
𝐴(−3;0)

OR

                         𝑥+3               
𝑥− 4𝑥 + 4 √𝑥− 𝑥− 8𝑥 + 12
𝑥− 4𝑥2 +4𝑥

     3𝑥− 12𝑥 + 12
    3𝑥− 12𝑥 + 12  
𝑓(𝑥) = (𝑥− 4𝑥 + 4)(𝑥 + 3)
𝐴(−3;0)

✔(𝑥−2)
✔(𝑥2 + 𝑥 − 6)
✔(𝑥−2)(𝑥−2)(𝑥+3) 
✔coordinates of 𝐴 (−3;0)

 

 


✔𝑥− 4𝑥 + 4
✔✔𝑥 + 3
✔coordinates of 𝐴 (−3;0)

(4)

     
10.2 𝑓′(𝑥) = 3𝑥− 2𝑥 − 8 = 0
(3𝑥 + 4)(𝑥 − 2) = 0
𝑥 = −4/3 or 𝑥 = 2
𝑓(−4/3) = (−4/3)3 −(−4/3)− 8(−4/3) +12
B(−4/3; 500/27 )

✔𝑓′(𝑥) 
✔𝑓′(𝑥)  = 0
✔correct 𝑥 value 𝑥 = −4/3
✔y = 500/27 

(5)

     
10.3

 𝑓′′(𝑥) = 6𝑥 − 2
6𝑥 − 2 = 0
𝑥 =1/3

OR

𝑥=−4/3+2
        2
𝑥=13

✔𝑓′′(𝑥) = 6𝑥 − 2
✔𝑥 =1/3
✔finding x value of  midpoint
✔𝑥 =1/3

(2)

     
 10.4  𝑥 <−4/3 or  𝑥 > 2

✔𝑥 <−4/3
✔𝑥 > 2

(2)

     
 10.5  𝑦=𝑘 ;𝑘<0
Only one Real Root

 ✔answer

(2)
[15]

QUESTION 11
 11.1  𝐷(0) = 3 + ½(0)2 −14(0)3
𝐷(0)=3 𝑚

✔𝐷(0)=3 𝑚

(1)

     
 11.2  𝐷′(𝑡) = 𝑡 − ¾𝑡2
𝐷′(3) =3 −¾(3)2
=3 − 27/4
=−15/4 m/h / m/u

✔𝐷′(𝑡)
✔𝐷′(3)
✔=−15/4 or -3.75

(3)

     
 11.3  Decreasing

✔Decreasing

(1)

     
 11.4  𝐷′(𝑡 )= 0
𝑡− ¾𝑡= 0
4𝑡 − 3𝑡= 0
𝑡(4 − 3𝑡) = 0
𝑡 = 0 or 𝑡 = 43
43 =1ℎ20𝑚𝑖𝑛
Time: at 08h00 or 9h20 

✔𝐷′(𝑡 )= 0
✔factors
✔t-values
✔answer

(4)
[9]

 

QUESTION 12

12.1 

12.1.1 

P(A′) = 1 − P(A) 
= 1 − 0,35 
= 0,65

✔ P(A′) = 1 − P(A) 
✔ answer

(2)

       
 

12.1.2 

P(AandB) = 0 
P(AenB) = 0

✔ answer

(1)

       
 

12.1.3 

P(A or B) = 0,35 + 0,52 
= 0,87

✔  P(A or B) = P(A) + P(B)
✔ answer

(2)

       

12.2 

12.2.1 

6! = 720 

✔ 6! or/of 720 

 (1)

       
 

12.2.2

4! 
= 24

✔4! 
✔ 24 

(2)

       
 

12.2.3

2!.5! =  240   = 1
  6!       720      3

OR 

0,333

✔ 2! 
✔ 5! 
✔ 6! 
✔ answer

(4) 
[12]

     

TOTAL: 150

Last modified on Tuesday, 15 June 2021 07:36