Tuesday

July 7, 2015

July 7, 2015

Total # Posts: 21,443

**pre - CALCULUS**

0 , 29/7 , 34/7 it says http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*April 11, 2015*

**pre - CALCULUS**

strange answer choices, arbitrary z hang on
*April 11, 2015*

**pre - CALCULUS**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*April 11, 2015*

**pre - CALCULUS**

But there is a limit to what I am going to try to type
*April 11, 2015*

**pre - CALCULUS**

oh ho, now Gauss Jordan. We are cooking with gas here
*April 11, 2015*

**Pre - CALCULUS**

LOL, I have not finished You need to do the whole ting all you know is termm 11 and 21 so far whoops 12 not +12 so element 11 is 5/12 and element 21 is -1/6 looks like C
*April 11, 2015*

**Pre - CALCULUS**

left determinant is D = -12 first solution is for +1 -6 +0 -5 or -5/12 = element 11 then +0 +1 -2 +0 over -12 or 2/-12 = -1/6 = A21 then do the second
*April 11, 2015*

**Pre - CALCULUS**

well, it may be time to ask what method you are supposed to use. for example you seem to have Cramer's rule so A * A*-1 = 1 0 over 0 1 so solve with 1 over 0 on the right then with 0 over 1 on the right so for first column of inverse solve +0 x - 6 y = 1 -2 x - 5 y = 0 ...
*April 11, 2015*

**Pre - CALCULUS**

I mean 9 :)
*April 11, 2015*

**Pre - CALCULUS**

+2 +4 -1 +1 -2 +2 ---> -4+40-1 -10-4-4 = 17 yuuk +5 +1 +1 now solve for Y not x because your solutions set has all different y values :) +2 32 -1 +1 -5 +2 ---> --10+320-20 -25-80-32 = 153 +5 20 +1 then 153/17 = ( whew, D
*April 11, 2015*

**pre - CALCULUS**

yes -4 * -1 = 1 and -4*3 = -12
*April 11, 2015*

**pre - CALCULUS**

note the determinant of 2 1 6 3 is 6 - 6 = 0 therefore the solutions using Cramer's Rule are undefined
*April 11, 2015*

**physics**

volume of iron = (4/3)pi (Rout^3-Rin^3) mass of iron = (1 g/cm^3)(4/3) pi Rout^3 so density of iron = Rout^3/(Rout^3-Rin^3)
*April 11, 2015*

**math**

18(4/3) = 24
*April 11, 2015*

**maths**

10^x * 10^y = 10^(x+y) (to multiply add exponents if the base is the same)
*April 11, 2015*

**NEED HELP PHYSICS!!!**

Ac = v^2/r = v^2/10.5 F = m Ac 3.22 = .0822 v^2 /10.5 solve for v
*April 11, 2015*

**PHYSICS HELP PLEASE !!**

F = m a tension = mg + m v^2/r F = 78.4 (9.81 + v^2/10)
*April 11, 2015*

**Calculus(urgent please help)**

vertical asymptotes is easy because x = 3 or -3 makes function undefined where is slope + and where - ? slope = ([x^2-9]2x - x^2[2x])/[x^2-9]^2 denominator is always + or 0 when is top + and -? top is -18x so slope = -18x/positive number so slope is + if x is + and - if x is...
*April 10, 2015*

**pre - CALCULUS**

You are welcome.
*April 10, 2015*

**pre - CALCULUS**

continuous A = P e^rt A = 11,000 e^(.065 *10) A = 11,000 * 1.9155 semiannual 20 periods at .0315 per period (6.3/2) 1.0315^20 = 1.859 A = 11,000 * 1.859 which is less :(
*April 10, 2015*

**Pre - CALCULUS**

well, I can not graph it very well but if exponential then y = Ae^kx x = year - 1985 12 = A e^0 = A(1) = A so y = 12 e^kx in 1994, x = 9 years y = 12 e^9k = 145 e^9k = 145/12 = 12 9 k = ln 12 = 2.48 k = .276 now in 2002 we would get x = 17 then we would get y = 12 e^(17*.276) ...
*April 10, 2015*

**Pre-calculus help**

tan is - in quadrants 2 and 4 cos is + in quadrants 1 and 4 so we are in quadrant 4, x = 6, y = -1 hypotenuse = sqrt (37) cute tan 2x = 2 tan x /(1-tan^2 x) = 2 (-1/6) /(1 - 1/36) =-(1/3) / (35/36) = -12/35 well that was easy now we better find out what quadrant 2x is in x is ...
*April 10, 2015*

**pre - CALCULUS**

so did I
*April 10, 2015*

**pre - CALCULUS**

Hey, I just did it.
*April 10, 2015*

**pre - CALCULUS**

to add two vectors you can add the components in orthogonal (perpendicular) directions and the sum will have components in those directions if u = a i + b j and v = c i + d j then u + v = (a+c) i + (b+d) j now here u+v = (-4+4) i + (1+1) j or 0 i + 2 j which is magnitude 2 in ...
*April 10, 2015*

**pre - CALCULUS**

I am not sure I understand your symbol. (absolute value?) anyway u + v = 2 j the magnitude of 2 j is 2
*April 10, 2015*

**Math 222**

Well, I told you number line eg so x is left of -3 or right of +2
*April 10, 2015*

**Math 222**

You are welcome.
*April 10, 2015*

**Math 222**

12 - x > 15 -x > 3 multiply both sides by -1 BUT change direction of arrow when changing signs x < - 3 (LOL - again) 7 x - 13 > 1 7 x > 14 x > 2 so x is left of -3 or right of +2
*April 10, 2015*

**Math 222**

divide it up into two problems 12 <12+ 4x 4 x >0 or x >0 and 12+4x <0 4 x < -12 x < - 3 so x is either left of -3 or right of 0 on a number line
*April 10, 2015*

**pre - CALCULUS**

The new graph has a point at (0,2), not at (0,0) The new graph has slopes of 2 and -2 instead of 1 and -1 in other words translate up[ 2 and double the slopes of the V shape
*April 10, 2015*

**pre - CALCULUS**

the point (2,2) (y must = x) becomes y = 2 |2| + 2 = 6 (y must equal 2 x+2) so (1,2) in the old graph becomes (1, 6) etc
*April 10, 2015*

**pre - CALCULUS**

no the point (1,1) becomes y = 2 |1| + 2 = 4 period, not 6 in other words (1,4)
*April 10, 2015*

**pre - CALCULUS**

f(x) = |x| is a V with point at origin and 45 degrees up in quadrants 1 and 2 move the whole thing up 2 and double the slopes try some points (0,0) ---> (0,2) (1,1) ---> (1,4) (-1,1) --> (-1,4) etc
*April 10, 2015*

**pre - CALCULUS**

theta +/- n (360) = theta so -404 + 360 = -44 which is indeed 44 degrees below the x axis in quadrant 4 ======================================== You could also call it + (360-44) = 316 counterclockwise from the x axis but if you are doing triangles for trig you would use that ...
*April 10, 2015*

**Calculus**

pi r^2 = 8 so r = 1.60 miles dA/dt = 2 pi r dr/dt yes, correct so 7.5 = 2 pi (1.6) dr/dt dr/dt = .748 miles/hr You used the area, 8 for the radius R
*April 10, 2015*

**Math**

Yes, you owe the principal of 2,000 plus the total interest which is 240
*April 10, 2015*

**math - plz help!!**

LOL, lots of ways but to reduce it to absurd: z = 3 5x - 4y = -z 2x + 7y = 5
*April 10, 2015*

**science ms sue plz help**

I agree with all your answers.
*April 10, 2015*

**physics**

Now Jhanvi, you are asking the same question over and over with slight changes. Figure out the time for each leg of your course. Figure out the total time by adding the times for each leg. Divide the total distance by the total time. That is your average speed.
*April 10, 2015*

**Maths**

a b c 55 times an integer 110 nope 165 nope 220 nope 275 SCORE!!!!!
*April 10, 2015*

**Physics**

by the way the relative density of steel is about 8
*April 10, 2015*

**Physics**

500 - 446 = 54 g = mass (not weight or force) of water displaced which is 54 cubic centimeters so density of block = 500 g/54 cm^3 = 9.26 g/cm^3 = 9260 kg/m^3 9260/1000 = 9.260 = relative density
*April 10, 2015*

**physics**

time at 80 t1 = 400/80 time at 100 t2 = 200/100 total time = t1 + t2 av speed = 600 / (t1+t2)
*April 10, 2015*

**physics**

look at my reply to your other problem, same way.
*April 10, 2015*

**math**

number of visitors can not be fractional therefore more than 31 and less than 33 31 < v < 33
*April 9, 2015*

**Calculus**

or more accurately i = 1000 e^kt 1200 = 1000 e^7k e^7k = 1.2 7 k = ln 1.2 k = .0260459367 as you said
*April 9, 2015*

**Calculus**

di/dt = k i di/i = k dt ln i = kt + c i = e^(kt+c) = C e^kt here 200/7 = k (1000) k = .02875 i = 1000 e^(.02875 t)
*April 9, 2015*

**Algebra**

(12x^5y^2z^3)/(9x^3y^3z) (9)(x)(y)(z)(12x^5y^2z^3)/(81 x^4 y^4 z^2) (108 x^6 y^3 z^4)/(9 x^2 y^2 z)^2 take sqrt 6 x^3 y z^2 sqrt(3y)/(9 x^2 y^2 z)
*April 9, 2015*

**Algebra**

in other words ^-12 a b^3 c^(7/6) a b^3 c^6/6 c^1/6 a b^3 c c^(1/6)
*April 9, 2015*

**Calculus**

e^-2y dy = 2 x dx e-2y /-2 = x^2 + c e^-2y = -2 x^2 + c -2y = ln (-2 x^2+c) when x = 0, y = 1 -2 = ln(c) e^-2 = c -2 y = ln (-2x^2+e^-2) y = -(1/2) ln(-2x^2+1/e^2)
*April 9, 2015*

**Math**

2^2 - 3 = 1 4^2 - 3 = 13 7^2 - 3 = 46 etc :)
*April 9, 2015*

**Calculus**

d^2x/dt^2 = -22 dx/dt = 132 - 22 t x = Xo + 132 t - (1/2)(22) t^2 so x to stop from 132 ft/s 0 = 132 - 22 t t = 6 seconds to get dx/dt = 0 then x = 132 (6) - 11 (36) x = 792 - 396 = 396 ft to stop so 4 feet to spare Now I think you can handle Robin';s unfortunate experience.
*April 9, 2015*

**science**

I believe so. Think what is happening. gravity on big mass squeezing center of mass harder and harder
*April 9, 2015*

**science**

You are welcome.
*April 9, 2015*

**science**

Yes, A elliptical is old stars, little gas or dust to make new ones. C and D are exactly wrong :)
*April 9, 2015*

**Calculus**

r-b = 8 r+b = 20 solve for r and b find r/(r+b) r-b = 10 r+b = 30 solve for r and b find r/(r+b)
*April 9, 2015*

**Math**

y = 10 + x/3 y + x = 46 so y = 46 - x 46 - x = 10 + x/3 36 = 4 x/3 x = 27 y = 46-27 = 19 ======================== 25 q + 10 d = 1205 d = 59 - q so 25 q + 590 - 10 q = 1205 etc
*April 9, 2015*

**science**

yes, sometimes one moves behind the other, masking the pair look dimmer
*April 9, 2015*

**math**

You are welcome :)
*April 9, 2015*

**math**

I said (1/5) x + 2 = x - 4 multiply everything both sides by 5 x + 10 = 5 x - 20
*April 9, 2015*

**math**

I do not know. Do you mean y=(1/5)x+2 y=x-4 then x + 10 = 5 x - 20 x = 30/4 = 15/2 = 7.5 or do you mean y = 1/(5x) + 2 then 1 + 10 x = 5 x^2 - 20 x solve quadratic or do you mean 1/(5x+2) = x-4 1 = (5x+2)(x-4) 1 = 5 x^2 + 18 x - 8 etc
*April 9, 2015*

**science**

I believe so.
*April 9, 2015*

**calc(steps and explanation also)**

D^2 = x^2 + y^2 2 D dD/dt = 2 x dx/dt + 2 y dy/dt or dD/dt = (x dx/dt + y dy/dt)/D at t = 0 x = 0 y = 150 at t = 10 x = 580 y = 150+100 = 250 D = sqrt(580^2+250^2) = 631.6 dx/dt = 58 dy/dt = 10 so plug into dD/dt = (x dx/dt + y dy/dt)/D
*April 9, 2015*

**math**

12 x - 3 = 2 x + 4 10 x = 7 x = 7/10 y = 2(7/10) + 4 y = 14/10 + 4 y = 5.4
*April 9, 2015*

**math**

600 = 5 n + 10 d + 25 q n = 10 d + q = 25 600 = 50 + 10 d + 25 q or 550 = 10 d + 25 q or 110 = 2 d + 5 q so 2 d + 5 q = 110 2 d + 2 q = 50 ---------------- 3 q = 60 q = 20 you take it from there.
*April 9, 2015*

**Calculus**

angle a = tan^-1 (.5) da/dt = -.25 deg/min = -.009436 radians/min x = 25 = y tan a y = 25/tan a dy/dt = -25 sec^2 a da/dt /tan^2 a
*April 9, 2015*

**physics**

F = 2.51 (9.81) - 3.08 (9.81) sin 32.3 = 8.48 N a = F/m = 8.48/(2.51+3.08) 2.51(9.81) - T = 2.51 a
*April 8, 2015*

**calculus**

feet, yuuk :( oh well, g = 32 ft/s^2 in that case Vi = 42 sin 16 = 11.6 ft/s u = 42 cos 16 = 40.4 ft/s Horizontal problem: goes 20 ft at 40.4 ft/s t = 20/40.4 = .495 s Vertical problem with t = .495 s -m g = m d^2h/dt^2 d^2 h/dt^2 = -g = -32 dh/dt = Vi - 32.2 t h = Hi + Vi t...
*April 8, 2015*

**math /fraction**

HUH? (1/3)(12) = 4
*April 8, 2015*

**calculus**

draw a picture ! (a) 5*2 = 10 4 + 10 = 14 (b) 2 * 4 = 8 Unless I am missing something :)
*April 8, 2015*

**calculus**

v = (1/3) base area * height for anything pointy with straight sides slant height = R cut away sector angle a sector angle remaining = 2pi-a base radius remaining =r= 2piR(2pi-a)/2pi = R(2 pi-a) height h = sqrt(R^2-r^2) v = (1/3)(pi r^2)h plug and chug
*April 8, 2015*

**Calculus (urgent help)**

http://www.jiskha.com/display.cgi?id=1428548293
*April 8, 2015*

**serious reply**

29 *47 ------ ones * ones 7*9 = 63 ones * tens 7*20 =140 tens * ones 40*9 = 360 tens * tens 40*20 = 800 add = 1363
*April 8, 2015*

**chemistry**

Mercury sulfide Chemical Compound Mercury sulfide, mercuric sulfide, mercury sulphide, or mercury sulfide is a chemical compound composed of the chemical elements mercury and sulfur. It is represented by the chemical formula HgS. "******It is virtually insoluble in water...
*April 8, 2015*

**Exponential Equations**

It doubles ten times t x 0 1000 18 2000 one time 36 4000 2 times 54 8000 3 times 72 16000 4 times or 1000*2^4 90 108 ...... 180 1024*1000 = 1,024,000 = 1000*2^10
*April 8, 2015*

**Math**

24 % of 100 is 24 29 % of 100 is 29 She has 29 from Norway and 24 from France so 29 - 24 = 5
*April 6, 2015*

**algebra**

y = -2 x^3 + b x^2 + c x + d y(0) = 2 so d = 2 y = -2 x^3 + b x^2 + c x + 2 1 = -2 + b + c + 2 or b+c=1 -2 = 16 + 4 b - 2 c + 2 or -20 = 4 b - 2 c or -10 = 2 b - c 2 b - 1 c = -10 1 b + 1 c = 1 ---------------- 3 b = - 9 b = -3 etc
*April 6, 2015*

**Physics**

convert this into a projectile problem. First solve for velocity of projectile needed to reach ground at 10 meters when fired at 45 deg from height of 1 m Call that V1 Now find V2, the new velocity Q2 = .5 Q1 = .5 * V1 * A1 and Q2 = V2 A2 so V2 = .5 V1 (A1/A2) = .5*(1/.2) * V1...
*April 6, 2015*

**physics**

I have no idea. At constant speed propulsion force = drag force and mass is not part of the problem.
*April 6, 2015*

**physics**

gravity p = rho g h
*April 6, 2015*

**physics**

v = 2 - 10 t y = 2 t - 5 t^2 x = 1 t so t = x y = 2 x - 10 x^2
*April 3, 2015*

**calculus**

length = L width = w A = L w cost = 400 = 10(2L+2w) = 20(2w) 400 = 20 L + 60 w 20 = L + 3 w L = 20 - 2 w A = 20 w - 2 w^2 dA/dw = 0 = 20 - 4 w w = 5 L = 10
*April 3, 2015*

**stastic**

Given the following information about a sample, calculate a z score for a test grade of 91. = 87, s = 4.01 (Points
*April 2, 2015*

**Algebra 2**

http://www.easycalculation.com/statistics/standard-deviation.php
*March 31, 2015*

**Algebra 2**

https://www.easycalculation.com/statistics/standard-deviation.php add up the squares of the difference between each value and the mean divide it by 7 or 6 depending on if the population sd or just sd is desired take the square root.
*March 31, 2015*

**physics**

1 hp = 550 ft lbs/s so 25 hp = 13,750 ft lbs/s = Torque *radians/sec 1800 rev/m (2 pi rad/rev)(1 m/60 s) = 188 radians/s so Torque = 13750/188 = 72.9 ft lbs
*March 31, 2015*

**science help.. pls help me dr.bob22 or damon**

In one case it is ionic In the other case it is covalent However In both cases it is chemical
*March 31, 2015*

**science help.. pls help me dr.bob22 or damon**

Water is a covalent bond but a special polarized one called a "hydrogen bond" that results in attraction between water molecules
*March 31, 2015*

**Algebra 2**

If c is the hypotenuse (opposite the right angle) then c^2 = a^2 + b^2 or b^2 = 361 - 9 b = sqrt(352) = 18.8 sin A = a/c sin B = b/c
*March 31, 2015*

**science help.. pls help me dr.bob22 or damon**

I think so.
*March 31, 2015*

**science help.. pls help me dr.bob22 or damon**

I suspect that finding that electrons surround a nucleus would be fatal for the hypothesis of indivisibility :)
*March 31, 2015*

**math - linear equation**

y = x y = -x
*March 31, 2015*

**science help.. pls help me dr.bob22**

been there done that below metals and halogens are likely to form ionic bonds
*March 31, 2015*

**pls help me dr.bob22 science**

Yes Oscar it is B. but you mean Zn + 2HCl = H2 + ZnCl2
*March 31, 2015*

**pls help me dr.bob22 science**

Yes
*March 31, 2015*

**pls help me dr.bob22 science**

If it is an ionic bond it is an ion K+ will do as will F- Cl2 is a complete molecule Ne is a noble gas which is too proud to react much.
*March 31, 2015*

**science help check**

Metals from Group 1 are most likely to form ionic bonds Halogens, group 17, are also likely to form ionic bonds
*March 31, 2015*

**Calculus - all the same question**

If you can follow the one I did, you can do the rest.
*March 30, 2015*

**Calculus**

dC/dx = 100 - .2 x at x = 35 dC/dx = 100 - 7 = 93 dollars per club at a level of 35 clubs by the way total C for 35 clubs = 3877.5 or about an average of 111 dollars per club
*March 30, 2015*