algebra 2 problem

Question

I need to find the value of f (1.6) and (1.9)
(x)=x^5-x^4+6x^3-4x^2-18x+8;[1.6,1.9]

 

this is my first year of this and I have no idea what to do, could someone please answer this problem with an explanation on how to do it in the future.

Answer 1

The notation f(1.6) is short for f(x=1.6).  Just plug 1.6 in for x in f(x) and compute the value of f(1.6). 

 

      f(x) = x⁵ - x⁴ + 6x³ - 4x² - 18x + 8

 

      f(1.6) = (1.6)⁵ - (1.6)⁴ + 6(1.6)³ - 4(1.6)² - 18(1.6) + 8 = ______

 

Same for f(1.9).

Answer 2

Hi there, Diane -

 

I'm assuming you are to insert 1.6 and 1.9 into the equation x^5-x^4+6x^3-4x^2-18x+8?

 

If this is the case then we do the following.  One, rewrite the equation with one value inserted in for x as thus:

 

(1.6)^5 - (1.6)^4 + 6*(1.6)^3 - 4*(1.6)^2 - 18*(1.6) + 8

 

Notice that I added some spaces where I saw it was appropriate.

 

OK, now we follow the order of operations which is:  ^ (power), * or / (multiplication or division), and then + or - (addition or subtraction).  Like operations are done left to right.

 

First, let's simplify by doing the power (^) operations by multiplying 1.6 by itself then number of times in the power:

 

10.48576 - 6.5536 + 6*4.096 - 4*2.56 - 18*1.6 + 8

 

Now let's do the multiplication, left to right:

 

10.48576 - 6.5536 + 24.576 - 10.24 - 28.8 + 8

 

The final step is to do the addition and subtraction, left to right:

 

-2.53184

 

Does this make sense?  I will leave inserting 1.9 into the equation for you to practice.

 

Let me know if I can help further!

 

Thanks,

Christopher