Question

solve this

$( \sqrt{5} + \sqrt{7} ) ( \sqrt{5} - \sqrt{7} )$
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Answer 1

Answer:

(a+b)(a-b)= a^2 -b^2

5-7 = -2 is the answer

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Answer 2

Answer:

$\boxed{-2}$

Step-by-step explanation:

We can solve it by using two methods.

• Simple multiplication.
• Using identity : a² - b² = (a + b) (a - b)

Solution:

→ I will be using simple multiplication.

$(\sqrt{5} + \sqrt{7} )( \sqrt{5} - \sqrt{7} ) \\ \sqrt{5} ( \sqrt{5} - \sqrt{7} ) + \sqrt{7} ( \sqrt{5} - \sqrt{7} ) \\ 5 - \sqrt{35} + \sqrt{35} - 7 \\ 5 - 7 \\ -2$

In the fourth step, - √35 got canceled with + √35.

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