√10 × √15 is equal to
a. 6√5
b. 5√6
c. √25
d. 10√5

Solution:

Given

√10 × √15

It can be written as

= √(2 × 5) × √(5 × 3)

We know that √ab = √a × √b

= 5 × √(2 × 3)

= 5√6

Therefore, √10 × √15 is equal to 5√6.

✦ Try This: √16 × √25 is equal to a. 6√5, b. 5√6, c. 20, d. 10√5

Given

√16 × √25

We know that √16 = 4 and √25 = 5

So we get

= 4 × 5

= 20

Therefore, √16 × √25 is equal to 20.

☛ Also Check: NCERT Solutions for Class 9 Maths Chapter 1

NCERT Exemplar Class 9 Maths Exercise 1.1 Problem 11

√10 × √15 is equal to a. 6√5, b. 5√6, c. √25, d.10√5

Summary:

Irrational numbers consist of non-terminating and non-recurring decimals. √10 × √15 is the multiplication of two irrational numbers. √10 × √15 is equal to 5√6

☛ Related Questions:

• The number obtained on rationalising the denominator of 1/(√7 - 2) is a. (√7 + 2)/3, b. (√7 - 2)/3, . . . .
• 1/ (√9 - √8) is equal to a. 1/2 (3 - 2√2), b. 1/(3 + 2√2), c. 3 - 2√2, d. 3 + 2√2
• After rationalising the denominator of 7/(3√3 -2√2), we get the denominator as a. 13, b. 19, c. 5, d . . . .