All Answers

GeometryKid:
On the calculater for this website how do you use the sin-1( , cos-1( , and tan-1(? I have try but when I go into 2nd there is no button for it.Can some one help me?

That is an easy one.
inverse sine is the same as arcsine.
and arc sine is abbreviated as asin
So it is

asin

etc

MelodyFeb 11, 2014

+6252

Quote:
2x^2+5x-3=0

this factors on inspection to (2x - 1)(x + 3) so the roots are given by

2x-1 = 0 ==> x = 1/2

x+3 = 0 ===> x = -3

RomFeb 11, 2014

+6252

Quote:
25x^2-16y^2

you should recognize this as the difference of two squares

(a ² - b ²) = (a + b)(a - b)

here a=5x, b=4y so

25x ² - 16y ² = (5x + 4y)(5x - 4y)

RomFeb 11, 2014

+6252

Quote:
Factor: 6x^2-13x-5

this doesn't quickly factor on inspection so I'd use the quadratic formula to solve for it's roots, r1 and r2.

Then the factors will be (x-r1)(x-r2) or something equivalent

here

a=6, b=-13, c=-5 so

r1,r2 = (13 +/- sqrt((-13) ² - 4(6)(-5)))[size=150]/[/size](2*6) =
(13 +/- sqrt(169 + 120))/12 =
(13 +/- 17)/12 = (30/12, -4/12) = (5/2, -1/3)

so 6x^2-13x-5 = 0 ==> (x-5/2)(x+1/3) = 0
we can rewrite this as (2x-5)(3x+1) = 0 and these are the two factors we are looking for.

So 6x^2-13x-5 = (2x-5)(3x+1)

RomFeb 11, 2014

+6252

Quote:
Solve The System Of Equations :3x+4y=11
x-2y=-3

3x + 4y = 11
x - 2y = -3

from the 2nd equation x = 2y - 3

plug that into the first

3(2y-3) + 4y = 11 ; multiply out
6y - 9 + 4y = 11 ; combine terms
10y = 20 ; divide both sides by 10
y=2
x = 2y-3 = 2(2)-3 = 1

(x,y) = (1,2)

RomFeb 11, 2014

+6252

Quote:
The speed of sound is 330m/s. The speed of light is 3x10^8m/s.

If the time between thunder and lightning is 3.5s, how far away is the storm?

You may as well assume that light is instantaneous so that the moment the lightning occurs you see it.

Then the distance from you to the bolt is the distance sound travels in 3.5s

That's just 330 m/s * 3.5 s = 1155 m

Just to show the assumption about light speed is ok the time that light take to travel this distance is

1155 / 3x10 ⁸ = 3.85 microseconds which is insignificant compared with the 3.5s it takes sound

RomFeb 11, 2014

Because i sit around all day getting head by your mom.

GuestFeb 11, 2014

eat my crum

GuestFeb 11, 2014

Because you have to multiply before you add so it would be 3x2 then add 5 and that equals 11

GuestFeb 11, 2014

+6252

Quote:
Construct the confidence interval for the population mean u.
c=0.90, x (it has a line over it)= 15.1, s=7.0, and n=100
A 90% confidence interval for u is (__,__). (Round to one decimal place as needed)

with n=100 your sample variance s' = s/sqrt(n) = s/10 = 7/10 = 0.7

so your sample distribution is Normal(15.1, 0.7)

c=.90 you need the lower tail to be at (1 - .9)/2 = 0.05

looking that up in your table you find that this corresponds to z = -1.64485

Your interval will thus be

(u + z s', u - z s') =
(15.1 - 1.64485*(0.7), 15.1 + 1.64485*(0.7)) =

(13.9, 16.3) to one decimal place.

RomFeb 11, 2014

+1313

well GUEST, the op would still need in the case she can't use a calculator to work out the remainder left as litre and some method to calculate. That would have been nice to give op a hand with given your insight.

StuFeb 11, 2014

+6252

google is your friend

1 mile = 5280 feet

RomFeb 11, 2014

+118725

Guest:
Sam traveled 3/4 of a journey by bus. He jogged 1/2 of the remaining distance and walked the rest of the way. If he walked 800 feet, what was the total distance he traveled?

I got 6,400 ft. Is this correct?

Let me see
3/4 by bus
1/4 left
1/2 of 1/4 is 1/8
He walked 1/8 th of the way and that was 800m
So the total distance was
8 x 800 = 6400feet. so your answer is excellent.
There are 5280 feet in a mile so that means sam travelled
6400 - 5280 = 1120 feet

So that means sam travelled 1 mile and 1120 feet.

MelodyFeb 11, 2014

Thanks for helping with the word problem with the fuel and everything. I finally figured it out.

GuestFeb 11, 2014

There is no reason to write that big. You might want to thank Rom for his help.

GuestFeb 11, 2014