Question

Докажите, что выражение 81 -3^2*4 кратно 5​пожалуйста срочно

Answer 1

$\displaystyle\bf\\81-3^{2} \cdot 4=81-9\cdot 4=81-36=9^{2} -6^{2} =(9-6)(9+6)=\\\\=3\cdot15=3\cdot 3\cdot 5$

Если один из множителей кратен 5 , то и всё произведение кратно 5 .

Answer 2

Checking the Divisibility of an Expression

To prove whether the expression \(81 - 3^2 \times 4\) is divisible by 5, we can evaluate the expression and check if the result is a multiple of 5.

Evaluating the Expression

Let's first evaluate the expression \(81 - 3^2 \times 4\):

\(3^2 = 9\)

Now, substitute the value of \(3^2\) into the expression:

\(81 - 9 \times 4\)

Perform the multiplication:

\(81 - 36\)

Now, subtract 36 from 81:

\(81 - 36 = 45\)

Checking for Divisibility by 5

To check if 45 is divisible by 5, we can perform the division:

\(45 \div 5 = 9\)

Conclusion

The result of the expression \(81 - 3^2 \times 4\) is 45, which is divisible by 5. Therefore, the expression is indeed divisible by 5.

The expression \(81 - 3^2 \times 4\) is divisible by 5.