# Important Questions for Class 8 Chapter 9-Algebraic Expressions and Identities

Mathematics is a tough subject. Do you think so? It is a very common notion among students to think that math is tough. For your benefit, our math subject experts have meticulously prepared a list of important questions for CBSE class 8 Math chapter-wise and topic-wise.

**Important questions based on NCERT syllabus for Class 7 Class 8 Chapter 9 - Algebraic Expressions and Identities:**

*Question 1*: Sandeep wants to buy 5 chocolates of Rs 10 each. He has to pay Rs 20 for parking also. If the price of chocolate is increased by Rs x, he decides to buy y less chocolates and he has to pay Rs z less for the parking. Write the arithmatic expression of the money spent by Sandeep.

Solution:

Price of chocolate = (10 + x)

No. of chocolates = (5 – y)

Parking fees = (20 – z)

Total money spent = (10 + x) (5 – y) + (20 – z)

*Question 2*:

(i) 5a^2b^2+10ab−12a^2+15b−20 and 34ab+24a^2+22b+24

(ii) abc+6bcd+abd−9ab+4bc−9a−43 and 4acd+10ac−54b−32c

(iii) 5bc+9ad−3c−12 and 24−5c−5b+2ab

Solution:

i) 5a^2b^2+10ab−12a^2+15b−20+34ab+24a^2+22b+24

= 5a^2b^2+44ab+12a^2+37b+4

(ii) abc+6bcd+abd−9ab+4bc−9a−43+4acd+10ac−54b−32c

= abc+6bcd+abd−9ab+4bc−9a−43+4acd+10ac−54b−32c

(iii) 5bc+9ad−3c−12+24−5c−5b+2ab

= 5bc+9ad−8c+12−5b+2ab

*Question 3*: Write the algebraic expression for:

(i) The volume of cube if its side(a) is reduced by 5.

(ii) Simple interest if time is reduced by 2 years and rate is increased by 5%.

(iii) Distance travelled if speed is increased by 5 units and time by 10 units.

Solution:

(i) Volume

=(a−5)^3

Here a is the initial length of the side of the cube.

(ii) Simple interest

=[P×(R+5)×(T−2)] / 100

P=Principal Amount

R=rate

T=Time

(iii) Distance = (s+5) (t+10)

s=speed

t=time