Question

☺Solve it ☺

☺Explanation Needed ☺​

Answer 1

Question :

Simplify :

1. $\sf{{(2a + b)}^{3} - {(2a - b)}^{3}}$
2. $\sf{{(3r - 2k)}^{3} + {(3r + 2k)}^{3}}$
3. $\sf{{(4a - 3)}^{3} - {(4a + 3)}^{3}}$
4. $\sf{{(5x - 7y)}^{3} + {(5x + 7y)}^{3}}$

Answer :

(all the answers are provided in the attachment)

Steps followed :

1. For finding out the solution we have used a single identity : $\sf{{(a+b)}^{3}}$. It's expansion can be traced as :$\sf{{a}^{3} + {b}^{3} + 3{a}^{2}b + 3a{b}^{2}}$
2. We have simplified each part of each sum and them either subtracted it or added it as directed.
3. Note that when we were asked to subtract the two numbers ; before doing so we have changed the signs of the solutions.