Question

It is given that 3a + 2b= 5c. find the value of 27 a³+8b³-125c³ if abc= 0

Answer 1

27a³ + 8b³ - 125c³= (3a)³+ (2b)³ + (-5c)³
3a + 2b = 5c
​3a + 2b - 5c = 0

Hence, ​(3a)³ + (2b)^3 + (-5c)³ = 3 (3a) (2b)(-5c)
= -90 abc = -90 x 0 = 0.ans...

hope this will help

Answer 2

$27a^3+8b^3-125c^3$
= $(3a)^3+(2b)^3+(-5c)^3$ (Mark as 1)

$3a+2b=5c$
= $3a+2b-5c=0$

Hence from (1), $3(3a)(2b)(-5c)$ (Identity used $a^3+b^3+c^3=3abc$)
= $-90abc$
= $-90(0)$
= 0