Page 150 - ICSE Math 7

Example 2: Write the following equations in statement forms.

(a) 3p + 4 = 26 (b) 3m = 6 (c) 5p – 2 = 18
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Solution: (a) Four added to three times a number p gives 26.
(b) Three-fifth of a number m is 6.
(c) Five times a number p minus 2 gives 18.

Example 3: Set up an equation in the following cases.
(a) Imran says that he has 3 marbles less than four times the marbles Rohit has. Imran
has 29 marbles.
(b) Garima’s father is 43 years old. He is 19 years older than twice the Garima’s age.
Solution: (a) Let Rohit have n marbles. (b) Let Garima’s age be y years.

Imran has 29 marbles. Garima’s father’s age = 43 years
∴ 4n – 3 = 29 ∴ 2y + 19 = 43

EXERCISE 13.1

1. Complete the following table.
Whether the equation
S. No. Equation Value
is satisfied (Yes/No)

(i) x – 5 = 0 x = 0
(ii) x + 7 = 2 x = –5

(iii) 3x – 24 = 0 x = 6

(iv) 16x + 16 = 0 x = –1

2. Check whether the value given in the brackets is the solution of the corresponding equation or not:
(a) x + 13 = 6 (x = –7) (b) 8x – 4 = 28 (x = 4) (c) 3p – 4 = 14 (p = 5)
3. Write equations for the following statements.
(a) The sum of nine times a and 6 is 24.
(b) A number b divided by 7 gives 5.
(c) If 12 is taken away from five times y, you get 40.
(d) Simran’s father is 41 years old. He is 5 years older than three times Simran’s age.
(e) In an isosceles triangle, the base angles are equal. Each of the base angle is double the vertex
angle.
(f) The sum of two consecutive odd numbers is 44.
4. Write the following equations in statement form.

(a) x + 7 = 9 (b) 3p = 16 (c) 4p + 2 = 20 (d) 2x – 5 = 20
p + 5

Trial and Error Method
An equation can be solved by trial and error method by substituting different values of the variable
till the equation is satisfied. Although this method is based on the definition, yet it is not convenient
to obtain the solution.

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