2. Expanding two brackets
(3 + t)(4 – 2t)
To expand or multiply out this expression, multiply every term in the second
bracket by every term in the first bracket.
(3 + t)(4 – 2t) = 3(4 – 2t) + t(4 – 2t)
= 12 – 6t + 4t – 2t2
= 12 – 2t – 2t2
This is a
quadratic
expression.
19. Basic steps
Look at equations
Same number of x’s or y’s?
If the sign is different, ADD the
equations otherwise subtract tem
Then have ONE equation
Solve this
Substitute answer to get the other
CHECK by substitution of BOTH
answers
20. Elimination Method
4x - 3y = 14
2x + 3y = 16
We have the same
number of y’s in each
If we ADD the equations,
the y’s disappear
+
6x = 30 Divide both sides by 6
x = 5
A
B
Substitute x = 5 in equation A
20 – 3y = 14
3y = 6
y = 2
Answer
x = 5, y = 2
21. Elimination Method
2x + 3y = 9
2x + y = 7
We have the same
number of x’s in each
If we SUBTRACT the equations,
the x’s disappear
-
2y = 2 Divide both sides by 2
y = 1
A
B
Substitute y = 1 in equation A
2x + 3 = 9
2x = 6
x = 3
Answer
x = 3, y = 1
22. What if NOT same number of x’s or y’s?
5x + 2y = 17
3x + y = 10
-
x = 3
In B
A
B
5 x 3 + 2y = 17
15 + 2y = 17
y = 1
Answer
x = 3, y = 1
If we multiply A by 2 we
get 2y in each
5x + 2y = 17
6x + 2y = 20
B
A
23. …if multiplying 1 equation doesn’t help?
3x + 7y = 26
5x + 2y = 24
-
29y = 58
In B
A
B
5x + 2 x 2 = 24
5x = 20
x = 4
Answer
x = 4, y = 2
Multiply A by 5 & B by 3,
we get 15x in each
15x + 35y = 130
15x + 6y = 72B
A
y = 2
Could multiply A by 2 & B
by 7 to get 14y in each
24. The sum of three consecutive integers is 54. What
are the three integers?
Three consecutive integers can be represented as
n, n + 1, n + 2.
n + (n + 1) + (n + 2) = 54
3n + 3 = 54
3n = 51
n = 17
Simplify left-hand side.
Subtract 3.
Divide by 3.
The three consecutive integers are 17, 18, and 19.
17 + 18 + 19 = 54.
Linear equation
27. x2
+ 4x -2=0
Start with the quadratic equatioStart with the quadratic equatio
Put in our values for a, b andPut in our values for a, b and c
Tidy upTidy up
You need to do this twice, once
adding and once taking away
You need to do this twice, once
adding and once taking away
and
x = -4.4 (1dp) and x = 0.4 (1dp)x = -4.4 (1dp) and x = 0.4 (1dp)
34. Here is a sequence of numbers.
What number is going
to come next in this
sequence?
0 2 4 6 8 10 12 14 16
Correct it is
the number
18
35. The nth term of an arithmetic sequence is given by:
The last # in the
sequence/or the #
you are looking for
First
term
The position
the term is in
The common
difference
un = a + (n – 1) d
36. Find the 14th
term of the
sequence 4, 7, 10, 13,……
(14 1)+ −4
4 (13)3= +
4 39= +
43=
un = a + (n – 1) d
u14 = 3
The 14th
term in this
sequence is the no. 43
45. Direct Variation
If y varies directly as x, then y = kx.
So if x = 2 and y = 10
Therefore, by substitution
What is the value of k?
10 = k(2).
10 = 2k
5 = k
46. Inverse Varation
Since Direct Variation is Y=kx
(k times x)
then
Inverse Variation is the opposite Y=k/x
(k divided by x)
47. inversely Variation
If y varies inversely as x, then y = k/x.
So if x = 2 and y = 10
Therefore, by substitution
What is the value of k?
10 = k/(2).
10(2) = k
20 = k
48. New Found Knowledge
Invented by =the Greek
mathematician Diophantus
He was also know as the father of
algebra
Year - 1637
49. Questions
1. , what is a, b and c?
- 2x2
+4x -3 =0
2. A table top measures x cm by y cm. Write down an
expression for its area, A.
3.
4. Evakutate - 7^2 + 12^2
●Solve 2x+3>x+5
Hinweis der Redaktion
Teacher notes
In this example, multiply everything in the second bracket by 3 and then everything in the second bracket by t. This can be written as 3(4 – 2t) + t(4 – 2t). As pupils become more confident, they can leave this intermediate step out.