Question

expand the following
(3a-2b)*3​

Answer 1

Question should be:

• Expand (3a-2b)³

ANSWER:

• Value of the above expression is 27a³-8b³-54a²b+36ab².

GIVEN:

• (3a-2b)³

TO FIND:

• Value of the above expression.

SOLUTION:

Formula:

• (a-b)³ = a³-b³-3a²b+3ab²

By Using this formula we can evaluate:

= (3a-2b)³

= (3a)³-(2b)³-3(3a)²(2b)+3(3a)(2b)²

= 27a³-8b³-54a²b+36ab²

Value of the above expression is 27a³-8b³-54a²b+36ab².

NOTE:

Some important formulas:

(a+b)² = a²+b²+2ab

(a-b)² = a²+b²-2ab

(a+b)(a-b) = a²-b²

(a+b)³ = a³+b³+3ab(a+b)

(a-b)³ = a³-b³-3ab(a-b)

a³+b³ = (a+b)(a²+b²-ab)

a³-b³ = (a-b)(a²+b²+ab)

(a+b)² = (a-b)²+4ab

(a-b)² = (a+b)²-4ab