Page 23 - Mathematics Class - IX

Viva-Voce

1. Expand: (x + y) 3
Ans. (x + y) = x + 3x y + 3xy + y 3
2
2
3
3
2. Find 12 using the above identity.
3
Ans. (12) = (10 + 2) = 10 + 3 × 10 × 2 + 3 × 10 × 2 + 2 3
3
3
2
3
2
= 1000 + 600 + 120 + 8 = 1728
3. What is the degree of (a + 2b) ?
3
Ans. 3
4. Is (p + q) a binomial?
3
Ans. No
5. Evaluate (3a + 1) .
3
Ans. (3a + 1) = 27a + 1 + 27a + 9a
3
3
2
6. What is the condition for (x + y) = 0?
3
Ans. Let (x + y) = 0
3
or x + y = 0 ⇒ x = –y
if x = –y, then (x + y) = 0
3
7. What is the condition for (x + y) = –ve?
3
Ans. Let (x + y) = –ve
3
then x + y = –ve
or x + y < 0 or x < –y
if x < –y, then (x + y) = –ve
3

MCQs

1. A cubic polynomial can have at the most
a) 2 zeroes b) 3 zeroes c) 1 zero d) no zeroes

2. A polynomial of degree 4 is called
a) cubic polynomial b) linear polynomial
c) bi-quadratic polynomial d) quadratic polynomial
3. Without multiplication evaluate (1.01) =
3
a) 1.0303 b) 1.030301 c) 1.03301 d) none of these
4. If p + q = 152 and p + q = 8 then the value of pq =
3
3
a) 14 b) 15 c) 160 d) none of these
5. Value of (50 + 1) is
3
a) 132651 b) 133651 c) 133261 d) none of these

Answers: 1. b) 3 zeroes 2. c) bi-quadratic polynomial 3. b) 1.030301
4. b) 15 5. a) 132651

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