Page 145 - ICSE Math 6

MENTAL MATHS

1. Fill in the blanks.

(a) 3ab + 2ab = __________ (b) 5pq – 6pq = __________
2

2
(c) 2a b + 3a b = __________ (d) 10xy – 2xy = __________
2
(e) 2ab × 6xy = __________ (f) –3x y × (–4) = __________
(g) –(a + x) = __________ (h) –(2 + xy) = __________
2
(i) –3 + 2x = –( ______ )
2. Write True or False.
(a) Sum of two unlike terms is a like term.
(b) Difference of two like terms is a like term.
(c) Product of a monomial and a number is a binomial.
(d) Product of two monomials is a monomial.

PRACTICE TIME

1. Add the following.
2
2
2
(a) 3a, 7a (b) –2x , 10x , 13x (c) 9ab, 2xy, –10ab
3 − 7 − 3 1
(d) a 4 , a 4 (e) p 2 , q , q p q (f) 3xy, –5xy, 2yz, –12yz
2
5 11 7 7
2. Subtract the following.
2
(a) 3xy from 5xy (b) 7m from 5mn (c) –12pq from –15pq
1
4
x y from 5x y
(d) 2 xy from – xy (e) 11 2 2 (f) 3mn from mn 3
3 5 13 7
3. Simplify.

2
2
2
2

(a) 18ab – 6b + 2ab + 2b + 5 (b) –3x – 10x + 5x 2
2
2
(c) 8p – 7p + 6q – 2p + 5p (d) ab – bc – ca + 5ab + 6bc – 9
2
2
2
2
2
(e) 2x + y – 3z + 6x – 5y (f) –10a + 6b – 5 + 13b – 10
4. Find the value of the following.
3
2
(a) –4x × 6 (b) (–3a) × (–5ab) (c) (–3x ) × (5y z)
2
2
5. What is the sum of 7 x y, 2x y and –mn?
13
1
6. Find the difference between 3 x + 2xy and 5x – y .
4 2
2
2
3
7. Multiply the product of (–3a b) and (4a ) by (–2ab ).
8. Simplify.
2
2
(a) 3a + (6a – 5) + 5 (b) 2xy + 3y – (2xy + y ) – (6 + 5)
(c) 5 – {2 × (3a – 2b) + 3} (d) 12 + [5 – {6 + 4(2p – 13p)}]
(e) 3{4x(5 – 6)} + 5y − 7y (f) 3 − {2ab + (3b − 5 ) 7b − b − 8ab }
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