Question

expand each of the following cubes using suitable identities:

(2x - 1)³​

Answer 1

Answer:

= 2x^3+1^3-2×2x×1

= 8+1-4x

= 4x+1

Answer 2

EVALUATION★

• $= (2x - 3) {}^{3}$

• We know that

• $= > (a - b) {}^{3} = a {}^{3} - b {}^{3} - 3a {}^{2}b + 3ab {}^{2}$

• comparison

• a=2x

• and b =3

• $= (2x) {}^{3} - 3 {}^{3} - 3(2x) {}^{2}(3) + 3(2x)(3) \\ \\ \\ = 8x {}^{3} - 27 - 3 \times 4x {}^{2} \times 3 + 6x \times 3 \\ \\ \\ = 8x {}^{3} - 27 - 36x {}^{2} + 18x$
• ______________________________

I hope it helps ✅you