TECHNICAL MATHEMATICS PAPER 1
GRADE 12
NATIONAL SENIOR CERTIFICATE
MEMORANDUM

JUNE 2018

NOTE:

  • If a candidate answers a question TWICE, only mark the FIRST attempt.
  • If a candidate has crossed out an attempt of a question and not redone the question, mark the crossed-out version.
  • Consistent accuracy (CA) applies to ALL aspects of the marking guideline.
  • Assuming answers/values to solve a problem is NOT acceptable.

QUESTION 1

1.1

111010
- 10101
1000012

🗸🗸Accurate value
(2)

1.2

1.2.1

x(x - 3) = 0
x = 0 or x = 3

🗸🗸Each correct x-value

(2)

 

1.2.2

x2 + 3x +1 = 0 (correct to ONE decimal)
x = - b ± √b2 - 4ac
               2a

x = -3 ± √(3)2 - 4(1)(1)  (-1 Mark for incorrect rounding)
                  2(1)  
x ≈ - 0, 4 or x ≈ - 2,6

OR

a

🗸 Formula

🗸Substitution

🗸 x ≈ -0,4

🗸 x ≈ -2,6

🗸 Each x value

🗸 Expansion

🗸Quadratic factors

🗸 x ≈ -0,4

🗸 x ≈ -2,6

(4)

  1.2.3

x2 + 3x + 2 < 0
(x+2) (x+1) < 0
Critical values : x = - 1 or x = -2

2

=>
-2 < x < -1

🗸Standard form

🗸Critical values

🗸Notation

🗸Both values

OR

🗸 🗸 🗸

-2 < x < -1

Accurate answer

🗸 -2< x

x < -1

(4)

1.3 

y = x2–1 …………. (1) and   y = x+1.................... (2)
x2–1 = x+1 x2 – x – 2 =0
(x +1) (x–2) = 0
x= 2 or x = –1
y = 3 or y = 0

🗸Equating (1) and (2)

🗸Standard form

🗸Factors

🗸Both x-values

🗸Both y-values

(5)

1.4

b2– 4ac = 0
b2– 4.1.4 = 0
b = 4 or b = – 4

🗸Discriminant = 0

🗸Substitution

🗸🗸Each value of b

(4)

 [21]

 

QUESTION 2

2.1

2x.21– 2x.2–1
       3.2x

= 2x(2 – 2–1) 
         3.2x
= 3 
   6
= ½ 🗸

🗸Prime bases

🗸 Factor 2x

🗸 Factor 2 – 2–1

🗸 ½

(4)

2.2

 1

🗸Log Rule(numerator)

🗸Log Rule (denominator)

🗸Simplification

  loga 5   –1 
 2loga 5–2

🗸Power rule

🗸Prime factors of 25

🗸Prime factors of 125

🗸Power rule (numerator)

🗸Power rule (denominator)

🗸Simplification

(5)

2.3
2.3.1

Rabbits = 1000 × 20,05(30)
Rabbits = 2828

🗸Substitution

🗸Answer

(2)

2.3.2 8000 = 1000 × 20,05t

8 = 20,05t
0, 05t = log28
t = 60 days

🗸Substitution

🗸log form

🗸 t = 60 days

(3)

    [14]

 

QUESTION 3

3.1

   

3.1.1

| Z |= √(–2)2  + (1)2
| Z |= √5

🗸Substitution

🗸Answer

(2)

3.1.2

 3

🗸Quadrant

🗸Point/Coordinates

(2)

3.1.3

tanθ = –½
θ = –26, 57o
θ = 180º – 26, 57º = 153, 43º

Accept angles in radians

🗸tan ratio

🗸Ref Angle

🗸Argument

(3)

3.1.4

 | Z |= √5
θ = 153, 43o
z = √5 [cos (153, 43o ) + isin (153, 43o )]

Accept angles in radians
OR

z = √3cis (153, 43o )

🗸🗸Accurate polar form

(2)

3.2

(x - yi) = –2+ i
              1+ i
x – yi = –2 + i  × 1 – i 
              1 + i     1 – i
x – yi = –2 + 2i +i – i2
                 1 – i2
x – yi = -1 + 3 i
             2     2
∴ x = -1 and y = - 3
          2                2

OR

1(x - yi) + i(x - yi) = –2 + i
x – yi + ix - y (i )2  = –2 + i x – yi + ix+ y = –2 + i
x+ y + ( x – y )i = –2+ i

x+ y = -2.............. (1)
x – y = 1................... (2)

(1)+(2) :

x = -½
and y = - 3
              2

🗸Simplification

🗸Conjugate product

🗸Simplification

🗸 x-value

🗸 y-value

🗸 Multiplication

🗸Simplification

🗸Comparing real values and imaginary values

🗸 x-value

🗸 y-value

(5)

[14]

 

QUESTION 4

4.1

  

4.1.1

inorm  = 14% = 0, 035
              4
= 3, 5%quarterly

🗸 Answer

(1)

4.1.2

 4

🗸Formula

🗸Substitution

🗸Interest

(3)

4.1.3

A = 2500(1 + 0, 035)7×4
A = R6550, 43

🗸Substitution

🗸Correct i = 0,035 and n = 21

🗸 Value of A

(3)

4.2

 
 5

In A1

i = 0, 08
       12
🗸n = 24
🗸 i = 0,1 = 0,025
         4
🗸n = 12
🗸 A1 = R687572,9508
In A2
🗸n = 8
🗸 A2 =R97 472, 2318
Final Amount R785045,18

(8)

     

[15]

 

QUESTION 5

5.1

      

5.1.1

0 = – ( x – 3)2  + 4
( x – 3)2  = 4
x – 3 = ±2
x = 5 or x = 1
A(1; 0) or B(5; 0)

OR
0 = -2+ 6x - 5
0 = (-x +1)(x - 5)
x = 5 or x = 1
A(1; 0) or B(5; 0)

🗸h(x) =0

🗸Transposition

🗸A co-ordinates

🗸B co-ordinates

🗸h(x) =0

🗸Factors

🗸A coordinates

🗸B coordinates

(4)

5.1.2

h(x) = -x2+ 6x - 5
dy = -2x + 5
dx
0 = -2x + 6
x = 3
h(3) = (3)2 + 6 (3) - 5
= 4
∴ D(3; 4)

dy
dx🗸

🗸Coordinates

(2)

5.1.3

x ∈ [0; 6] OR 0 ≤ x ≤ 6

🗸0

🗸6

🗸Correct notation

(3)

5.1.4

Maximum height = 4 units

🗸Answer

5.1.5

y-intercept of h = –5
Beams have height of 5 units

🗸y-intercept

🗸 5 units

(2)

5.1.6

y ≤ 4 OR y Î (-∞; 4] OR - ∞ < y ≤ 4

🗸 Notation

🗸 Value(s)

(2)

5.1.7

x ∈ [3;5] OR 3 ≤ x ≤ 5

🗸3

🗸5

🗸Correct notation

(3)

5.2

No. The truck height (4,5) is greater than the
bridge height (4 units) and the bridge has cross bars on top.

🗸 No

🗸 Bridge less than truck height

OR Truck height greater than the bridge height

🗸Cross bar

(3)

5.3 

At F, x = 3

y = – 3+5 =2

FD = D – F
FD = 4 – 2
FD = 2 units

🗸y-value at F

🗸Subtracting y-values

🗸 FD

(3)

    [23]

Related Items

 

QUESTION 6

6.1

  

6.1.1

0 = –2 + 1
       x
x = 2
(2; 0)

🗸y =0

🗸 Coordinates

(2)

6.1.2

f(x) = 20

y =1

🗸 Value of y

(1)

6.1.3

y=0 for f(x)

x = 0 and y =1 for g(x)

–1 Mark for 1 omitted asymptote

 

🗸y =0

🗸x =0 and y=1

(2)

6.2

 6

🗸Shape of f

🗸 y-intercept of f

🗸 y=1 Asymptote of g

🗸 1 more point on f

🗸Shape of g

🗸 1 more point on g

🗸 x- intercept of g

(7)

6.3

 

6.3.1

x ∈ R, x ≠ 0

🗸Restriction

🗸Domain value

(2)

6.3.2

x ∈ (0; +∞ ) OR x > 0

🗸Correct inequality

(1)

       [15]

 

QUESTION 7

7.1

f (' x)= lim  f ( x+ h) –  f ( x)
         h→0          h

f '(x)= lim –2 ( x+ h)2  – (–2x2 )
        x→0            h

f (x)= lim  –2x2 – 4xh – 2h2 + 2x2
       x→0                 h
f'(x)= lim h (–4x – 2h)
       x→0        h
f '(x)= –4x

🗸Formula

🗸Substitution

🗸Expansion

🗸Factors

🗸 f '(x)= –4x

(5)

-1 Mark for incorrect notation in 7.1 or 7.2

7.2

y = 2√x – 1
                x
y = 2x½ – x-1

dy = x½ + x-2
dx

OR

dy = 1  + 1 
dx   x½   x2

🗸2x½ 

🗸x-1

🗸 x½ 

🗸x-2

7.3

g'(x) = 2x - 2
mtangent = 2(2) – 2 = 2
y = 22– 2.2 = 0
(2; 0)
y = mx+c
0 = 2.2 + c
c = – 4
y = 2x – 4

🗸 g'(x)

🗸 mtangent

🗸(2;0)

🗸 c = – 4

🗸 y = 2x – 4

(5)

 

 

[14]

 

QUESTION 8

8.1

f (–1) = (–1)3 + 4(–1)2 + (–1) – 6
f (–1) = – 4 ≠ 0
So x+1 is not a factor of f(x) because f (–1) is not equal to 0.

🗸f (–1) = – 4 ≠ 0

8.2

f (1) = (1)3 + 4(1)2 + (1) - 6 = 0
(x -1) is a factor of f

       1        4         1           -6
1     0        1         5            7
       1        5         6            0

f(x) = (x–1) (x2+5x+6)
f(x) = (x–1) (x+3) (x+2)
x =1 or x = –3 or x = –2
(1;0), (–2;0), (–3;0)

🗸 f(x) =0

🗸 First linear factor

🗸Quadratic factor

🗸Factors of x2+5x+6

🗸All coordinates

(5)

8.3

y-intercept = –6

🗸Answer

(1)

8.4

f '(x)= 3x2+ 8x+1
0 = 3x2 + 8x+1
x= – 8 ± √64 – 4.3.1
               2.3
x = – 0,13 or x = –2, 54
(– 0,13; – 6, 06) or (– 2, 54; 0,89)

🗸 f '(x) = 0

🗸x- values

(-0,13; -6,06)

(-2,54; 0,89)

OR

Y – coordinates of TP

🗸 y= -6, 06

🗸 y= 0,89

8.5 

 7

🗸Shape

🗸x-intercepts

🗸Max. Turning point

🗸Min. Turning point

🗸 y-intercepts

(5)

 

 

[16]

 

QUESTION 9

9.1

  

9.1.1

Surface Area = 2(2x.x +2x.h + x.h)
4x2 + 4xh + 2xh = 120
6x.h = 120 – 4x22

∴ h = 120 - 4x2
            6x
h = 20 - 2x
       x     3

🗸 Formula

🗸Substitution

🗸 Simplification

🗸 h

(3)

9.1.2

V = l.b.h
8

🗸V = l.b.h

🗸Substitution

(2)

9.1.3

dV = 40 – 4x2
dx
0 = 10 – x2
x = √10 or x ≠ - √10

🗸 dV
   dx
🗸 dV = 0
    dx

🗸 x = 10 ≈ 3,16 cm3

(3)

9.2  

T = t3 - 9t 2+ 50t - 66
dT = 3t 2 -18t + 50
dt
dT = 3(5)2 -18(5) + 50
dt
dT = 35º C.s-1
dt

🗸 3t 2 -18t + 50

🗸Substitution by 5

dT =35 C.s-1
dt🗸 

(3)

   

 

[11]

 

QUESTION 10

10.1

 

9 

🗸 x3

🗸 - x 2
      2

🗸 c

10.2

 10

🗸Integration expression

🗸Simplification

🗸Substitution by 1 and 0

🗸 1 square units
   6

(4)

    [7]

TOTAL:150

Last modified on Friday, 13 August 2021 08:13