Question

Evaluate (2a + 3b) (2a-3b)​

Answer 1

Answer:

(2a + 3b) (2a-3b)

= (2a)²-(3b)²

= 4a²-9b²

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Answer 2

Evaluate -

• (2a + 3b) (2a-3b)

Solution -

Identity to be used -

$\boxed{\sf{\red{(a - b) (a + b) = a^2 - b^2}}}$

↬ $\sf{(2a + 3b) (2a-3b)}$

↬ $\sf{(2a)^2 - (3b)^2}$

↬ $\sf{4a^2 - 9b^2}$

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Know more -

Some useful identities -

• $\sf\green{{(a - b)}^{2} = {a}^{2} + {b}^{2} - 2ab}$

• $\sf\green{{(a + b)}^{2} = {a}^{2} + {b}^{2} + 2ab}$

• $\sf\green{(a + b)^3 = a^3 + b^3 + 3ab(a + b)}$

• $\sf\green{(a - b)^3 = a^3 - b^3 - 3ab(a - b)}$

Signs are changed on the following bases -

• (-) (-) = (+)

• (+) (+) = (+)

• (-) (+) = (-)

• (+) (-) = (-)