Question

3. Find the cube of:
i. (2a + 3b) ii. (3x - 4y) iii. (4 + 5m) iv. (p + q)

Answer 1

Answer:

$(2a + 3b) {}^{3} = 8a {}^{3} + 27b {}^{3} + 36a {}^{2} b + 54ab {}^{2}$

$(3x + 4y) {?}^{3} = 27x {}^{3} - 64y {?}^{3} - 108x {}^{2} y + 144xy {}^{2}$

$(4 + 5m) {}^{3} = 64 + 125m {}^{ 3} + 240m + 300m {}^{2}$

$(p + q) {}^{3} = p { }^{3} + q {}^{3} + 3p {}^{2} q + 3pq {}^{2}$

Answer 2

Answer:

(2a + 3b) {}^{3} = 8a {}^{3} + 27b {}^{3} + 36a {}^{2} b + 54ab {}^{2}(2a+3b)

3

=8a

3

+27b

3

+36a

2

b+54ab

2

(3x + 4y) {?}^{3} = 27x {}^{3} - 64y {?}^{3} - 108x {}^{2} y + 144xy {}^{2}(3x+4y)?

3

=27x

3

−64y?

3

−108x

2

y+144xy

2

(4 + 5m) {}^{3} = 64 + 125m {}^{ 3} + 240m + 300m {}^{2}(4+5m)

3

=64+125m

3

+240m+300m

2

(p + q) {}^{3} = p { }^{3} + q {}^{3} + 3p {}^{2} q + 3pq {}^{2}(p+q)

3

=p

3

+q

3

+3p

2

q+3pq

2