The side of a regular hexagon is denoted by l. Express the perimeter of the hexagon using l.

The perimeter of the triangle shown in Fig. 7.1 is

Give expressions in the following cases:

(a) 11 added to 2m

(b) 11stbtracted from 2m

(c) 5 times yto which 3 is added

(d) 5 times yfrom which 3 is subtracted

(e) y is multiplied by -8

(f) y is multiplied by -8 and then 5 is added to the result

(g) yis multiplied by 5 and the result is subtracted from 16

(h) y ismultiplied by -5 and the result is added to 16

Give expressions for the following cases:

(a) 7 added to p

(b) 7 stbtracted from p

(c) p multiplied by 7

(d) p divided by 7

(e) 7 subtracted from –m

(f) -p multiplied by 5

(g) -p divided by 5

(h) p multiplied by -5

Form expressions using y, 2 and 7. Every expression must have y in it. Use only two number operations. These should be different.

Form expressions using t and 4.

Use not more then one number operation.

Every expression must have t in it.

The diameter of a circle is a line segments which joins two points on the circle and also passes through the centre of the circle. (In the adjoining figure AB is a diameter of the circle; C is its centre.) Express the diameter of the circle (d) in terms of its radius (r).

A cube is a three-dimensional figure as shown in the adjoining figure. It has six faces and all of them are identical squares. The length of an edge of the cube is given by l. Find the formula for the total length of the edges of a cube.

Which out of the following are expressions with numbers only?

(a) y + 3

(b) (7×20) – 8z

(c) 5(21-7)+7×2

(d) 5 (e) 3x

(f) 5 – 5n

(g) (7×20) – (5×10) – 45 + p

To find sum of three numbers 14, 27 and 13, we can have two ways:

(a) We may first add 14 and 27 to get 41 and then add 13 to it to get the total sum 54 or

(b) We may add 27 and 13 to get 40 and then add 14 to get the sum 54.

Thus, (14 + 27) + 13 = 14 + (27 + 13).

This can be done for any three numbers. This property is known as the associativity of addition of numbers. Express this property which we have already studied in the chapter on Whole Numbers, in a general way, by using variables a, b and c.

The side of a regular hexagon is denoted by l. Express the perimeter of the hexagon using l.