S.chand publication New Learning Composite mathematics solution of class 7 Chapter 4 Powers and Exponents Exercise 4A

 Exercise 4A

---

Q1 | Ex- 4A | Class 7 | Schand | New Learning Composite mathematics | Chapter 4 | Powers and Exponents | myhelper

OPEN IN YOUTUBE

Question 1

Complete the table. One has been done for you.

	Expression	Base	Exponent	Meaning	Value
(a)	28	2	8	2 x 2 x 2 x 2 x 2 x 2 x 2 x 2	256
(b)	(-12)3
(c)	(-3/4)4
(d)	(-5/7)3

Sol :

	Expression	Base	Exponent	Meaning	Value
(a)	28	2	8	2 x 2 x 2 x 2 x 2 x 2 x 2 x 2	256
(b)	(-12)3	-12	3	(-12)×(-12)×(-12)	-1728
(c)	(-3/4)4	$\frac{-3}{4}$	4	$\frac{-3}{4}\times \frac{-3}{4} \times \frac{-3}{4} \times \frac{-3}{4}$ $=\frac{-3\times -3 \times -3 \times -3}{ 4\times 4\times 4\times 4}$	$\frac{81}{256}$
(d)	(-5/7)3	$-\frac{5}{7}$	3	$\frac{-5}{7} \times \frac{-5}{7} \times  \frac{-5}{7}$ $=\frac{-5\times -5\times -5}{7\times 7\times 7}$	$\frac{-125}{343}$

---

Q2 | Ex- 4A | Class 7 | Schand | New Learning Composite mathematics | Chapter 4 | Powers and Exponents | myhelper

OPEN IN YOUTUBE

Question 2

Write in exponential form.

(a) 15×15

Sol : (15)²

(b) (-9)×(-9)×(-9)

Sol : (-9)³

(c) 29

Sol : (29)¹

(d) $\left(-\frac{5}{7}\right) \left(-\frac{5}{7}\right) \left(-\frac{5}{7}\right) \left(-\frac{5}{7}\right)$

Sol : $\left(\frac{-5}{7}\right)^4$

(e) (-8) (-8) (-8)….10 times

Sol : (-8)¹⁰

(f) (2p) (2p) (2p)

Sol : (2p)³

(g) (-x). (-x). (-x). (-x)

Sol : (-x)⁴

(h) (-10) . (-10) a. a. a

Sol : (-10)²a³

(i) (-m). (-m) . (-m). n. n

Sol : (-m)³n²

(j) – 43

Sol : (-43)¹

---

Q3 | Ex- 4A | Class 7 | Schand | New Learning Composite mathematics | Chapter 4 | Powers and Exponents | myhelper

OPEN IN YOUTUBE

Question 3

Find the value of each expression.

(a) 5³

Sol : 125

(b) -5³

Sol : -125

(c) $\left(-\frac{2}{9}\right)^3$

Sol : $-\frac{8}{729}$

(d) (-2)⁶

Sol : 64

(e) (-3)⁴

Sol : 81

---

Q4 | Ex- 4A | Class 7 | Schand | New Learning Composite mathematics | Chapter 4 | Powers and Exponents | myhelper

OPEN IN YOUTUBE

Question 4

Write each expression as repeated multiplication. Then write the value of each expression.

(a) 10⁴

Sol : 10×10×10×10=10000

(b) $\left(-\frac{7}{8}\right)^4$

Sol : $-\frac{7}{8} \times -\frac{7}{8} \times -\frac{7}{8} \times -\frac{7}{8}=\frac{2401}{4096}$

(c) $\left(\frac{1}{10}\right)^2$

Sol : $\frac{1}{10} \times \frac{1}{10}=\frac{1}{100}$

(d) (-12)³.y⁴

Sol : (-12)×(-12)×(-12) × y.y.y.y

=-1728.y⁴

Q5 Ex- 4A Class 7 Schand chapter 4 Powers and Exponents

OPEN IN YOUTUBE

Question 5

Express the prime factorization of the following numbers in exponential form.

(a) 81

Sol : (3)⁴

(b) 1600

Sol : 2⁶.5²

(c) $-\frac{32}{243}$

Sol : $\left(-\frac{2}{3}\right)^5$

(d) $-\frac{343}{1331}$

Sol : $\left(-\frac{7}{11}\right)^3$

Q6 Ex- 4A Class 7 Schand chapter 4 Powers and Exponents

OPEN IN YOUTUBE

Question 6

Express:

(a) 625 to base (i) 5 (ii) 25

Sol :

(i) 5⁴

(ii) 25²

(b) -729 to base (i) 3 (ii) -9

Sol :

(i) -(3)⁶

(ii) (-9)³

Q7 Ex- 4A Class 7 Schand chapter 4 Powers and Exponents

OPEN IN YOUTUBE

Question 7

Evaluate:

(a) (-3)³ x (-1)⁹ x 10²

Sol :

=-27×-1×100

=2700

(b) (-2/3)³ (-3/4)² x (-1)⁸ x (-6)²

Sol :

$=-\frac{8}{27} \times \frac{9}{16} \times 1 \times 36$

=-6

Question 8

Evaluate each expression for the given value of the variables.

(a) a^m+bⁿ for a = -5, b = 11, m = 3 and n = 2

Sol :

=(-5)³+11²

=-125+121=-4

(b) 3x¹⁵ – (y + z)³ for x = -1, y = -7, z = -3

Sol :

=-3(-1)¹⁵-(-7-3)³

=3(-1)¹⁵-(-10)³

=-3+1000=997