Chapter 7: Algebra

Solution:-

(B) Unknown quantities

Solution:-

(A) Can take different values

The word ‘variable’ means something that can vary, i.e., change. The value of a variable is not fixed. We use a variable to represent a number and denote it by any letter such as l, m, n, p, x, y, z etc.

Solution:-

(C) x is subtracted from 10

Solution:-

(A) x – 1700

From the question it is given that,

Savitri has a sum of Rs x

She spent money on groceries = ₹ 1000

She spent money on clothes = ₹ 500

She spent money on education = ₹ 400

She received gift = ₹ 200

Total money spent by Savitri = 1000 + 500 + 400 = ₹ 1900

Then,

Total money left with her after deducting = ₹ (x – 1900)

Therefore, money left with her after adding gift money = (x – 1900) + 200

= x – 1700

Solution:-

(A) 2x + y

Given triangle is an isosceles triangle,

So, perimeter of an isosceles triangle = 2 × x + y

= 2x + y

Solution:-

(A) x × x

We know that, area of square = side × side

Given, square having a side x.

So, area of a square = x × x

= x²

Solution:-

(C) 3 – 2x

From the question it is given that,

X is multiplied by 2 = x × 2 = 2x

Then, x is multiplied by 2 and then subtracted from 3 = 3 – 2x

Solution:-

(A) 6

Consider the given equation q/2 = 3

By cross multiplication we get, q = 6

Solution:-

(B) 2

Consider the given equation x – 4 = -2

Transform – 4 from left hand side to right hand side it becomes 4.

x = – 2 + 4

x = 2

Solution:-

(A) numerical equation

4/2 = 2

By cross multiplication we get,

4 = 4