Ws9 Solving Simple Algebraic Equations I

Date:

______/______/ 2009

Marks

Worksheet 9: Solving Simple Algebraic Equations I 1

Basic Solve the following equations. 2 2 (a) +5 = 3x 5 2 (b) =4 3x − 1

Solution:

(a)

Cross Multiply

2 +5= 3x 2 = 3x 2 = 3x

2 5 2 −5 5 −23 5

10 = −69 x x=−

(b)

2 =4 3x − 1 2 = 12 x − 4 6 = 12 x x=

1 2

10 69

[Anglican High School/ 2007] 10 1 Ans: (a) − (b) 69 2

© Victoria School Math Department

2

Basic Given the formula p =

c − 3d 2 (c − 3d ) 2

, find the value of p when c =10 and d = 2.

Solution:

p=

c − 3d 2 (c − 3d )2

10 − 3(2) 2 [10 − 3(2)]2 10 − 12 = 42 −2 = 16 1 =− 8

=

[Anglican High School / 2007] 1 Ans: p = − 8

3

Basic Solve the following equations (a) 8x + 4 = 3x – 7 2 y + 3 3 y − 15 (b) = 3 11

Solution: (a) 8 x + 4 = 3 x − 7 5 x = −11 11 x=− 5 1 = −2 5

2 y + 3 3 y − 15 = 3 11 22 y + 33 = 9 y − 45

(b)

13 y = −78 y = −6

[Bukit Panjang Government High School / 2007] 1 Ans: (a) −2 (b) −6 5

© Victoria School Math Department

4

Basic Find the value of u when v = 9 and f = 5 in the formula Solution:

1 1 1 + = . u v f

1 1 1 + = u v f 1 1 1 + = u 9 5 1 1 1 = − u 5 9 4 = 45 45 u= 4 1 = 11 4

[Anglican High School / 2007] 1 Ans: u = 11 4

5

Intermediate Solve the following equations: (a) (b)

34 − 2 x = 2 ( 5 − 4 x ) − 6 x 2 ( x − 2) 3

+ 12 =

3 ( x + 1) 2

Solution:

(a) 34 − 2 x = 2 ( 5 − 4 x ) − 6 x 34 − 2 x = 10 − 8 x − 6 x −2 x + 8 x + 6 x = 10 − 34 12 x = −24 x = −2

(b)

2 ( x − 2)

+ 12 =

3 ( x + 1)

3 2 2 x − 4 + 36 3 x + 3 = 3 2 2 ( 2 x + 32 ) = 3 ( 3 x + 3) 4 x + 64 = 9 x + 9 64 − 9 = 9 x − 4 x 55 = 5 x x = 11

[Xinmin School / 2007] Ans: (a) x = −2 (b) x = 11

© Victoria School Math Department