Questions · Page 3 of 3

1 Marks Question

Question 1011 Mark
The sum of the multiplication table of natural number ‘n’ is given by 55 × n. Find the sum of:
Table of 7
Answer
Given, the sum of multiplication table of n natural numbers = 55 × n
Sum of table of 7 = 55 × 7 = 385 [put n = 7]
View full question & answer
Question 1021 Mark
The sum of the multiplication table of natural number ‘n’ is given by 55 × n. Find the sum of:
Table of 19
Answer
Given, the sum of multiplication table of n natural numbers = 55 × n
Sum of table of 19 = 55 × 19 = 1045 [put n = 19]
View full question & answer
Question 1031 Mark
The sum of the multiplication table of natural number ‘n’ is given by 55 × n. Find the sum of:
Table of 10
Answer
Given, the sum of multiplication table of n natural numbers = 55 × n
Sum of table of 10 = 55 × 10 = 550 [put n = 10]
View full question & answer
Question 1041 Mark
Subtracting a term from a given expression is the same as adding its additive inverse to the given expression.
Answer
True.
Solution:
Because additive inverse is the negation of a number or expression.
View full question & answer
Question 1051 Mark
Subtract 9a2 - 15a + 3 from unity.
Answer
In order to find solution, we will subtract 9a2- 15a + 3 from unity, i.e. 1. Required ‘expression is
1 - (9a2- 15a + 3)
= 1 - 9a2 + 15a -3
= -9a2+ 15a - 2
View full question & answer
Question 1081 Mark
Find the values of the following polynomials at a = -2 and b = 3:
$\frac{\text{a}^2-\text{b}^2}{3}$
Answer
Given a = -2 and b = 3
So,
putting a = -2 and b = 3in the given expressions
we get:
$\frac{\text{a}^2-\text{b}^2}{3}=\frac{(-2)^2-(3)^2}{3}=\frac{4-9}{3}=\frac{-5}{3}$
View full question & answer
Question 1091 Mark
Find the values of the following polynomials at a = -2 and b = 3:
$\frac{\text{a}^2+\text{b}^2}{3}$
Answer
Given a = -2 and b = 3
So, putting a = -2 and b = 3in the given expressions we get.
$\frac{\text{a}^2+\text{b}^2}{3}=\frac{(-2)^2+(3)^2}{3}=\frac{4+9}{3}=\frac{13}{3}$
View full question & answer
Question 1101 Mark
Find the values of the following polynomials at a = -2 and b = 3:

$\frac{\text{a}}{\text{b}}+\frac{\text{b}}{\text{a}}$

Answer
Given a = -2 and b = 3
So,
putting a = -2 and b = 3in the given expressions
we get:
$\frac{\text{a}}{\text{b}}+\frac{\text{b}}{\text{a}}=\frac{(-2)}{3}+\frac{3}{(-2)}$
$=\frac{-2}{3}-\frac{3}{2}=\frac{-4-9}{6}=\frac{-13}{6}$
[$\because\ $LCM of 2 and 3 is 6]
View full question & answer
Question 1111 Mark
Find the values of the following polynomials at a = -2 and b = 3:
a3 - 3a2b + 3ab2 - b3
Answer
Given a = -2 and b = 3
So, putting a = -2 and b = 3in the given expressions we get.
a3 - 3a2b + 3ab2 - b3
= (-2)3 - 3(-2)2 - (3) + 3(-2) (3)2 - (3)3
= -8 - 36 - 54 - 27 = -125
View full question & answer
Question 1121 Mark
Find the values of the following polynomials at a = -2 and b = 3:
a3 + 3a2b + 3ab2 + b3
Answer
Given a = -2 and b = 3
So, putting a = -2 and b = 3in the given expressions we get.
a3 + 3a2b + 3ab2 + b3
= (-2)3 + 3(-2)2 (3) + 3(-2) (3)2 + (3)3
= -8 - 36 - 54 - 27
= 1
View full question & answer
Question 1131 Mark
Find the values of the following polynomials at a = -2 and b = 3:
a2 - 2ab + b2
Answer
Given a = -2 and b = 3
So, butting a = -2 and b = 3in the given expressions we get.
a2 - 2ab + b2
= (-2)2 - 2(-2) (3) + (3)2
= 4 + 12 + 9
= 25
View full question & answer
Question 1141 Mark
Find the values of the following polynomials at a = -2 and b = 3:
a2 + b2 - ab - b2 - a2
Answer
Given a = -2 and b = 3
So,
putting a = -2 and b = 3in the given expressions we get.
a2 + b2 - ab - b2 - a2
= (-2)2 + (3)2 - (-2) (3) - (3)2 - (-2)2
= 4 + 9 + 6 - 9 - 4
= 6
View full question & answer
Question 1151 Mark
Find the values of the following polynomials at a = -2 and b = 3:
a2 + 2ab + b2
Answer
Given a = -2 and b = 3
So, butting a = -2 and b = 3in the given expressions we get.
a2 + 2ab + b2
= (-2)2 + 2(-2) (3) + (3)2
= 4 - 12 + 9
= 1
View full question & answer
Question 1161 Mark
Find the values of following polynomials at m = 1, n = -1 and p = 2:
m3 + n3 + p3
Answer
Given, m = 1, n = -1 and p = 2
So,
putting m = 1, n = -1 and p = 2 in the given expressions
we get:
m+ n+ p3
=(1)3 + (-1)3 + (2)3 
=1 - 1 + 8
= 8
View full question & answer
Question 1171 Mark
Find the values of following polynomials at m = 1, n = -1 and p = 2:
m3 + n3 + p3 - 3mnp
Answer
Given, m = 1, n = -1 and p = 2
So,
putting m = 1, n = -1 and p = 2 in the given expressions
we get:
m3 + n3 + p3 - 3mnp
= (1)3 + (-1)3 + (2)3 - 3(1) (-1) (2)
= 1 - 1 + 8 + 6
= 14
View full question & answer
Question 1181 Mark
Find the values of following polynomials at m = 1, n = -1 and p = 2:
m2 + n2 + p2
Answer
Given, m = 1, n = -1 and p = 2
So,
putting m = 1, n = -1 and p = 2 in the given expressions
we get:
m+ n+ P2
= (1)2 + (-1)2 + (2)2
= 1 + 1 + 4
= 6
View full question & answer
Question 1191 Mark
Find the values of following polynomials at m = 1, n = -1 and p = 2:
m2n2 + n2p2 + p2m2
Answer
Given, m = 1, n = -1 and p = 2
So,
putting m = 1, n = -1 and p = 2 in the given expressions
we get:
m2n2 + n2p2 + p2m2
= (1)2× (-1)2 + (-1)2 × (2)2 + (2)2 × (1)2
= 1 + 4 + 4
= 9
View full question & answer
Question 1201 Mark
Find the values of following polynomials at m = 1, n = -1 and p = 2:
m + n + p
Answer
Given, m = 1, n = -1 and p = 2
So,
putting m = 1, n = -1 and p = 2 in the given expressions
we get:
m + n + p
= 1 - 1 + 2
= 2
View full question & answer
Question 1211 Mark
Find the values of following polynomials at m = 1, n = -1 and p = 2:
mn + np + pm
Answer
Given, m = 1, n = -1 and p = 2
So,
putting m = 1, n = -1 and p = 2 in the given expressions
we get:
mn + np + pm
= (1) (-1) + (-1) (2) + (2) (1)
=1 - 2 + 2
= -1
View full question & answer
Question 1221 Mark
Express the following properties with variables x, y and z:
Distributive property of multiplication over addition.
Answer
We know that,
Distributive property of multiplication over
addition, a × (b + c)
= a × b + a × c
$\therefore\ $Required expression is x × (y + z)
= x × y + x × z
View full question & answer
Question 1231 Mark
Express the following properties with variables x, y and z:
Commutative property of multiplication.
Answer
We know that,
Commutative property of multiplication, axb
= bxa
$\therefore $Required expression is x × y
= y × x
View full question & answer
Question 1241 Mark
Express the following properties with variables x, y and z:
Commutative property of addition.
Answer
We know that,
Commutative property of addition, a + b
= b + c
$\therefore $ Required expression is x + y
= y + x
View full question & answer
Question 1251 Mark
Express the following properties with variables x, y and z:
Associative property of multiplication.
Answer
We know that,
Associative property of multiplication, a × (b × c)
= (a × b) × c
$\therefore \ $Required expression is x × (y × z)
= (x × y) × z
View full question & answer
Question 1261 Mark
Express the following properties with variables x, y and z:
Associative property of addition.
Answer
We know that,
Associative property of addition, a + (b + c)
= (a + b) + c
$\therefore $Required expression is x + (y + z)
= (x + y) + z
View full question & answer
Question 1271 Mark
Critical Thinking Write two different algebraic expressions for the word phrase $\Big(\frac{1}{4}\Big)$  of the sum of x and 7.
Answer
First expression $=\frac{1}{4}(\text{x} +7)$
As we know, the addition is commutative.
So, it can also be written as $\frac{1}{4}(7+\text{x})$
View full question & answer
Question 1281 Mark
A wire is (7x - 3) metres long. A length of (3x - 4) metres is cut for use. Now, answer the following questions:
How much wire is left?
Answer
Given, length of wire = (7x - 3)m
And wire cut for use has length = (3x - 4)m
Left wire = (7x - 3) - (3x - 4)
= 7x - 3 - 3x + 4
= 7x - 3x - 3 + 4
= (4x + 1)m.
View full question & answer
Question 1311 Mark
3x + 23x2 + 6y2 + 2x + y2 + ____________ = 5x + 7y2.
Answer
3x + 23x2 + 6y2 + 2x + y2 + M = 5x + 7y2.
Solution:
Let (3x + 23x2 + 6y+ 2x + y2) + M = 5x + 7y2
⇒ M = (5x + 7y2) - (3x + 23x2 + 6y+ 2x + y2)
⇒ M = 5x + 7y- 3x - 23x– 6y2 - 2x - y2
⇒ M = 5x - 3x - 2x + 7y- 6y- y2 - 23x2
M = 0 + 0 - 23x2 = -23x2
[with - ve sign, + ve sign in the bracket will change on opening it]
View full question & answer
1 Marks Question - Page 3 - MATHS STD 7 Questions - Vidyadip