Question

If a- 2b +3c =0 prove that a³ -8b³+ 27c²= - 18abc​

Answer 1

Explanation:

the answer is in the photo as attached

Answer 2

Use the identity:

• x³ + y³ + z³ = 3xyz if x + y + z = 0

Substitute:

• x = a, y = -2b, z = 3c

to get

• a³ + (-2b)³ + (3c)³ = 3a(-2b)(3c)
• a³ - 8b³ + 27c³ = --18abc