help please

[czagara]

I have figured out the answer to the problem I am working on however the book wants an approximation and I have no idea how to do the caculation on my caculator.
The answer is -1+-2 squareroot 7
Can someone please help? Thanks!

 

[Mrspi]

I have figured out the answer to the problem I am working on however the book wants an approximation and I have no idea how to do the caculation on my caculator.
The answer is -1+-2 squareroot 7
Can someone please help? Thanks!

Follow the order of operations (PEMDAS)

-1 + -2 sqrt(7)

There are no "operational" grouping symbols, so start with the exponent...YES...sqrt indicates a power or exponent.

find sqrt(7) first....
then do the multiplication....-2 * sqrt(7)
then do the addition: -2*sqrt(7) + 1

 

[czagara]

i think i am writing the answer wrong because they are looking for an approximate decimal

 

[Mrspi]

i think i am writing the answer wrong because they are looking for an approximate decimal

sqrt(7) is NOT a whole number (nor even a rational number). Round sqrt(7) to a reasonable number of decimal places... three would probably be plenty. Then complete the operations, and round your answer to two or three decimal places.

 

[czagara]

i understand what you are saying but i don't know what to punch in first on the caculator. i just have a regular caculator and i keep coming up with the wrong answer every which way i plug it in

 

[czagara]

i got 2.646 for the squareroot of 7 and i'm not really sure what to do next???

 

[mmm4444bot]

i'm not really sure what to do next?

Follow the three steps, at the end of Mrs. Pi's first reply.

You just did the first step:

sqrt(7) = 2.646

Now, do the next two steps (in order).