Question

Preeti has solved a question in her exam using the following method. In which step has she gone wrong and what is the correct answer obtained after the calculation?
Question: $(2p{)}^3+3p^3=11p^3+a$. Find the value of a.
step i: $6p^3+3p^3=11p^3+a$
Step ii: $9p^3=11p^3+a$
step iii: $-2p^3=a$

• A. i,
• B. ii,
• C. i, 0
• D. iii, 0

Answer 1

The correct option is C

i, 0

$(2p{)}^3+3p^3=11p^3+a$
step i: $8p^3+3p^3=11p^3+a$
Step ii: $11p^3=11p^3+a$
step iii: a = 0. So, step i is wrong as $(2p{)}^3$ is not equal to $6p^3$ but $(2p{)}^3$ equals $8p^3$.