Showing posts with label simple maths. Show all posts
Showing posts with label simple maths. Show all posts

Linear Inequalities


An inequality is just like linear equation which has two sides and an unknown variable which are always represented with alphabets (a-z) but deals with a lot of signs.
Signs of inequalities
> Greater than
< Less than
≥ Greater or equal to
≤ Less than or equal to

Solve the following inequalities;

Example 1; Simplify 2x – 4 > 8

Solution

Note;
In order to do this, you must consider the two sides of this inequality.








2x – 4 > 8 (Make x the subject of the equation)

2x > 8 + 4

2x > 12 (Divide both sides by 2)

x > 6.

Example 2; Solve the inequalities 3x – 8 ≤ 10 + 5x

Solution

3x – 8 ≤ 10 + 5x (Collect like terms)

3x – 5x ≤ 10 + 8

- 2x ≤ 18 (Divide both sides by the co-efficient of x which is -2)

x ≥ - 9.

Note; the inequality sign must change when dividing with a minus sign).


Practice these questions below;
1. Simplify 4x – 1/3     2/3x + 2


3. Simplify 6x – 2 < 2x + 8
4. Simplify 1/3y  >  1/2y  +  1/4
5. Simplify 6/x    2

FRACTIONS


A fraction is part of a whole number which contains a numerator and denominator. A numerator is the figure placed on top while the denominator is the figure placed below. There are three types of fractions which are;

1. Proper Fraction; This is a fraction which has its numerator lower than the denominator E.g. ½, 2/5, 7/9, etc.

2. Improper Fraction; This has its numerator higher (bigger) than the denominator. E.g.  3/2, 4/3, 9/5, etc.

3. Mixed Fractions; This consists of a whole number and a proper fraction written together. E.g. 11/2, 23/4, 56/7, etc.

Solving any question related to fractions shouldn’t be difficult if students can master the term BODMAS. BODMAS stands for the order which arithmetic are carried out, which are as follows;

B; Bracket
O; Of
D; Division
M; Multiplication
A; Addition
S; Subtraction

Example 1; Simplify 52/3 ÷ (232/5 of 31/4 – 22)

Note;
Before applying the BODMAS rule to this question, you will have to convert all the mixed fractions to proper fractions. You can do these by multiplying the whole number with first the denominator and second add the result with the numerator and finally dividing your total result with the denominator. (This is the format of conversion; Whole Number × Denominator + Numerator ÷ Denominator).

= 17/3 ÷ (117/5 of 13/4 – 22)

Applying the rule means you’ll first deal with the ones in bracket where “of” stands for multiplication.
= 17/3 ÷ (117/5 × 13/4 – 22)
= 17/3 ÷ (1521/20 – 22)

Find the L.C.M of the fractions in bracket;
= 17/3 ÷ (1521/20440/20)

= 17/3 ÷ (1081/20)

Remove the bracket;
= 17/3 ÷ 1081/20

Note;
It is impossible to divide two fractions, so you’ll have to change the mathematical sign to multiplication (It’s a rule in mathematics) which makes the fraction to the right take an inverse form.

= 17/3 × 20/1081

= 340/3243 (Answer).

Example 2; Evaluate








Convert all mixed fractions to proper fractions;
 

 




Find the L.C.M of both fractions above and below;





 




= 11/4 ÷ 11/8 (Change division sign to multiplication sign just like example 1 above)

= 11/4 × 8/11 (11 cancels 11 while 4 in 8 gives 2)

= 2 (Answer).


Practice these questions below;

Simplify the following;

1. (a) 23/4 + 32/5 – 11/2
    (b) 21/6 + (33/5 ÷ 11/8)
    (c) (25/6 – 31/2) ÷ 11/2 of 52/3


2. Simplify this fraction; 






3. (a) 5/9 ÷ (13/81/3)
    (b)  51/3 ÷ (45/6 – 31/5)
    (c) 21/2 ÷ (21/4 ÷ 41/3)
 
4. Simplify this fraction below;