1)a student buys a pen and writes with it. what kind of economic activity is this​

15.5% Nitrogen, 18.5% Calcium

Answer:

Fibonacci, also known as Leonardo Bonacci, Leonardo of Pisa, or Leonardo Bigollo Pisano, was an Italian mathematician from the Republic of Pisa, considered to be "the most talented Western mathematician of the Middle Ages".

Answer:

c) 0

d) -27/6

Step-by-step explanation:

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Answer:

[tex]\qquad \:\boxed{\begin{aligned}& \qquad \:\sf \: (c) \: \: 0 \qquad \: \\ \\& \qquad \:\sf \: (d) \: \: \dfrac{ - 9}{2} \end{aligned}} \qquad \\ \\ [/tex]

Step-by-step explanation:

[tex]\large\underline{\sf{Solution-c}}[/tex]

Given expression is

[tex]\sf \: \: ... \: \times \: \dfrac{ - 9}{11} = 0 \\ \\ [/tex]

Let assume that missing value be x

So,

[tex]\sf \: \: x \: \times \: \dfrac{ - 9}{11} = 0 \\ \\ [/tex]

[tex]\sf \: \: x \: = \: 0 \: \div \: \dfrac{ - 9}{11} \\ \\ [/tex]

[tex]\sf\implies \sf \: \: x \: = \: 0 \: \\ \\ [/tex]

Hence,

[tex]\qquad\qquad\boxed{ \sf{ \:\bf \: \: 0 \: \times \: \dfrac{ - 9}{11} = 0 \: }} \\ \\ [/tex]

[tex]\large\underline{\sf{Solution-d}}[/tex]

Given expression is

[tex]\sf \:\dfrac{6}{ - 27} \: \times \: ... \: = \: 1 \\ \\ [/tex]

Let assume that missing value be x.

[tex]\sf \:\dfrac{6}{ - 27} \: \times \: x \: = \: 1 \\ \\ [/tex]

[tex]\sf \:x \: = \: 1 \: \div \: \dfrac{6}{ - 27} \: \\ \\ [/tex]

[tex]\sf \:x \: = \: 1 \: \times \: \dfrac{ - 27}{6} \: \\ \\ [/tex]

[tex]\sf \:x \: = \: \dfrac{ - 27}{6} \: \\ \\ [/tex]

[tex]\sf\implies \sf \:x \: = \: - \: \dfrac{9}{2} \: \\ \\ [/tex]

Hence,

[tex]\qquad\qquad\boxed{ \sf{ \: \bf \:\dfrac{6}{ - 27} \: \times \: \dfrac{ - 9}{2} \: = \: 1 \: }}\\ \\ [/tex]

Step-by-step explanation:

(x+y)²–(x–y)²

(x+y+x-y){(x+y)-(x-y)}

(2x)(x+y-x+y)

(2x)(2y)

4xy

a²-b²=(a+b)(a-b)

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Answer:

Step-by-step explanation:

Answer:

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