Tuesday

February 21, 2017
Total # Posts: 1,812

**chemistry**

not enough nitrogen a mole of nitrogen is needed for every 3 moles of hydrogen

*February 20, 2017*

**math**

tan(?) = 250/170

*February 20, 2017*

**Math**

v = 24 (1 + .06)^385

*February 20, 2017*

**physics**

2 * vertical velocity / g 16.7 * ?2 / 9.81

*February 20, 2017*

**Algebra**

(a) m = 500 (1 + .015)^t (b) 800 = 500 (1 + .015)^t ... 1.6 = 1.015^t ... log(1.6) = t log(1.015) ... [log(1.6)] / [log(1.015)] = t

*February 20, 2017*

**Algebra - PLEASE HELP!**

231 = -17.5x2^ - 138.5x - 27 462 = -37 x^2 - 277 x - 54 0 = -37 x^2 - 277 x - 516 use quadratic formula to find x

*February 20, 2017*

**probability**

there are 9 pairs of cards that differ by one ... 1-2, 2-3, 3-4, etc. there are 10C2 possible pairs ... 45 so the probability of a pair differing by one is 9/45 or .2 ... by more than one is (1 - .2) = .8 3 cards contain 3 pairs .8^3 = .512

*February 19, 2017*

**physics**

m g h = 1/2 m v^2 ... v = ?(2 g h)

*February 19, 2017*

**physics**

it's a fraction of a mole ... 9.1E5 / 6.02E23 multiply the fraction by the molar mass

*February 19, 2017*

**physics**

60 sec in a min 2.54 cm in an inch 9.843E4 ft/min * (1 min / 60 s) * ... (12 in / 1 ft) * (.0254 m / 1 in)

*February 19, 2017*

**physics**

f = m a = 2E3 kg * ... [(20 m/s - 5 m/s) / 4 s] answer is in Newtons

*February 19, 2017*

**Algebra2**

an = 13n - 8

*February 19, 2017*

**Physics**

convert mph to m/s convert cg(?) to kg K.E. = 1/2 m v^2

*February 19, 2017*

**physical science**

Joules of energy required ... 202 * (95.6 - 22.0) * 4.18 divide by heater wattage ... 1 watt = 1 Joule per second divide by 60 ... sec to min

*February 19, 2017*

**Physics**

friction

*February 19, 2017*

**science**

free fall...starting from rest d = 1/2 g t^2 ... plug in the times, and find the difference in the distances the 1st body will always be going faster than the 2nd, so the distance between them is always increasing

*February 19, 2017*

**Math**

the edge length is the cube root of the volume 8 in this case

*February 19, 2017*

**Math**

not enough information

*February 19, 2017*

**Maths**

the distance between the centers of the two outer circles is 4 they are in the diagonal corners, and their centers are ?2 from the corners so the diagonal of the square is ... 4 + 2?2 dividing by ?2 to find side length ... 2 + 2?2 squaring ... 4 + 4?2 + 4?2 + 8 = 12 + 8?2

*February 19, 2017*

**Math**

order counts 6P3

*February 18, 2017*

**physics**

the work ... 7.6N * 8.6m ... is equal to the block's KE 1/2 * 0.50 * v^2 = 7.6 * 8.6

*February 18, 2017*

**Math 125**

sometimes just using numbers will clarify for 2000 people ... 10 have the virus ... 8 will test pos ... 2 will not ... 1990 do not have the virus ... 199 will test pos a) 207 people test pos ... 8 of them have it ... 8/207 = .0386 b) 1793 people test neg ... 2 of them have it...

*February 18, 2017*

**physics**

20^2 = 10^2 + v^2 sin(?) = 10/20 ... north of west

*February 17, 2017*

**College Chem**

heat gained by water equals heat lost by metal 50.0 * (t - 20.0) * 4.182 = ... 1000 * (100.0 - t) * 0.50

*February 17, 2017*

**Physics**

you know the size of the disk, and the material (aluminum) calculate the volume and look up the density

*February 17, 2017*

**Physics 202-help**

15/3 = 5 ... storm distance in km 15s * 343m/s = theoretical distance the time for the light to travel is below the sig fig of the other measurements ... it can be considered instantaneous

*February 17, 2017*

**backwards math**

(6 + 6 - 5) * 4

*February 17, 2017*

**Algebra**

u = t + 7 10u + t = 3(10t + u + t + u) ... = 33t + 6u 4u = 32t solve the system by substitution or elimination

*February 16, 2017*

**math**

x (154) + (40 - x)(170) = 40 (160)

*February 16, 2017*

**Math**

v / 125 = [v / (125 + 25)] + 4/3

*February 15, 2017*

**Physics**

1) the sound goes over and back ... 2 w =5.7 * 343 2)velocity = frequency * wavelength ... v = (2.22 / 7.59) * .168 m

*February 15, 2017*

**Physics**

3 s measures the km to the lightning 5 s measures the miles

*February 15, 2017*

**Algebra**

(k - 10)(k - 2) (2x + 7)(3x - 2)

*February 15, 2017*

**maths**

45 * (1 + .10)^20

*February 15, 2017*

**too-hard probability sir damon/reiny/steve help**

"you can lead a horse to water...but you can't make him drink"

*February 15, 2017*

**too-hard probability sir damon/reiny/steve help**

this is binomial...with a twist P(b) = .4 , P(w) = .6 (b + w)^4 b^4 + 4 b^3 w + 6 b^2 w^2 + 4 b w^3 + w^4 P(w ? 0) = 1 - P(b = 4) = 1 - .4^4 P(b = 2) = 6 * .4^2 * .6^2 divide to find the conditional

*February 15, 2017*

**Physics**

the given data is unrealistic please check it

*February 15, 2017*

**physics**

the ball is uniformly accelerated by gravitational force the velocity is zero at the peak 1.5 s before the peak, the velocity is ... 1.5 * g upward 1.5 s after the peak, the velocity is ... 1.5 * g downward

*February 14, 2017*

**PreCalc**

18 t + 5 t - 5 = 12

*February 14, 2017*

**Algebra 2**

x y = k

*February 14, 2017*

**Algebra 2**

the job takes 96 people-hours so for 3 people... 96/3 hr

*February 14, 2017*

**Exponential Equation**

4E12 = 24 * e^388r ln(1.7E11) / 388 = r

*February 14, 2017*

**Math**

3 1/2 is 28 eighths

*February 14, 2017*

**Math**

the scale is logarithmic 10^(8.3 - 6.2)

*February 14, 2017*

**Geometry**

the four given sides sum to 24 so the 5th side is 6 ... 30 - 24

*February 14, 2017*

**Algebra**

x + 2y = 150 x + 4y = 260 solve the system

*February 14, 2017*

**physics**

the net force is ... f = m a ... f = 111.5 * 2.7 net force is tension minus gravity t = 111.5 (9.8 + 2.7)

*February 13, 2017*

**Chemistry**

2 KClO3 ---> 2 KCl + 3 O2 moles O2 = 3/2 * moles KCl moles KCl = mass KCl / molar mass KCl mass O2 = moles O2 * molar mass O2

*February 13, 2017*

**chemistry**

find grams of C in CO2 and grams of H in H2O convert the grams to moles (divide by the molar masses) the mole ratio will give you the empirical formula

*February 13, 2017*

**college algebra**

h = 1/2 g t^2 + v t + Ho 44 = -4.9 t^2 + 20 t + 37 solve the quadratic for t

*February 13, 2017*

**Math! Please help!**

15 ? -k/4 - 9 24 ? -k/4 96 ? -k ... -96 ? k

*February 13, 2017*

**Chemistry**

381 pm is the edge length of the cubic unit cell the atomic radius is the edge length multiplied by ... ?2 / 4

*February 13, 2017*

**Math**

2 is 12/6 so you need the lowest common multiple of 12 and 5 ... 60 60/6 = 10 ... five 2 lb bags

*February 13, 2017*

**math**

looking at the cross section, this is a circle in an equilateral triangle

*February 13, 2017*

**math**

looks good

*February 13, 2017*

**math**

plug the points into the general equation and solve the system P...1 = a - b + c Q...1 = a + b + c R...6 = 25a + 5c + c

*February 13, 2017*

**math**

P and Q are the same point need 3 DIFFERENT points

*February 13, 2017*

**Chemistry**

22.4 L/mole ... gas at stp octane is 114 g/mole 2 C8H18(g) + 25 O2(g) ---> 16 CO2 (g) + 18 H2O(l) (39.0 / 114) * 12.5 * 22.4 L

*February 12, 2017*

**physics**

work = force * distance f = 5497 / 22.1 a = f / m = 5497 / (22.1 * 3090) d = 1/2 a t^2 ... t = ?(2d / a) v = a t

*February 12, 2017*

**Algebra**

3a + 9c = 183 ... 6a + 18c = 366 6a + 13c = 276 subtract equations to eliminate a solve for c, then substitute back to find a

*February 12, 2017*

**Algebra**

(r + 3) / 79 = r / 15 15 r + 45 = 79 r

*February 12, 2017*

**sciance**

depends on the car

*February 12, 2017*

**Physics**

yes the up-thrust (bouyancy) is a function of the VOLUME of liquid displaced

*February 12, 2017*

**grade7 math**

the rectangle with the least perimeter is a square

*February 12, 2017*

**Chemistry**

you aren't given the atomic mass not enough data for a solution

*February 11, 2017*

**Chemistry**

the volume of hexane is ... 338 g / .66 g/mL the height of the liquid is ... (hexane vol) / (? *2.91^2)

*February 11, 2017*

**physics**

energy = 1/2 m v^2 energy / time = power

*February 11, 2017*

**Algebra 2**

a^b = 3^3 3^(1/2)^x = a^(1/6) 3^3^x = a 3^3 = a^(1/x) x = 1/b

*February 11, 2017*

**math**

the slope is the same everywhere on the line slope = (-5 - 7) / (-5 - 4)

*February 11, 2017*

**math**

the distance is constant, so speed and time are inversely proportional t / 28 = 65 / 78

*February 11, 2017*

**Math**

c (100% - 56%) = 202.92

*February 10, 2017*

**Math**

m = [(91 - 44.39) / 44.39] * 100%

*February 10, 2017*

**physics**

how thick is the ice?

*February 9, 2017*

**math**

adding equations to eliminate e ... 3d = 12 solve for d, then substitute to find e

*February 9, 2017*

**Math**

3.36E6 poeple / 3 per household = ... 1.12E6 households 2 bags per month = 24 bags per year ... 10 lbs per bag 1.12E6 * 24 * 10 = ?

*February 9, 2017*

**Math**

a square m is 10000 square cm

*February 9, 2017*

**chem**

it will appear that there are more moles of solute than are actually present you will be dividing the mass of added solute by too large a number ... this will result in the molar mass being too low

*February 9, 2017*

**geometry**

the two angles sum to 180º x + (4x + 50) = 180

*February 9, 2017*

**Chemistry**

that's what you start with ... some of it is precipitated out also, the volume of the solution is more than doubled (remaining PbCl2) / solution volume

*February 9, 2017*

**Science ms sue please help**

the question specifies "chemical property"

*February 9, 2017*

**Science ms sue please help**

if there is no reaction...what are you observing?

*February 9, 2017*

**algebra**

c + r = 4.5 14c + 8r = 51 solve by substitution or elimination

*February 9, 2017*

**Mathematics**

x = -3 (y + 1) x^2 = 9 (y^2 + 2y + 1) substitute and solve for y there will probably be two solutions ... the intersection(s) of a circle and a line

*February 9, 2017*

**Algerbra**

the vertex is on the axis of symmetry ... x = -b / 2a f(x)=x^2+2x-3 ... x = -2 / 2*1 = -1 f(x)=x^2-3x+1 ... x = - -3 / 2*1 = 3/2 plug the x's into their functions to find the y's for the vertex coordinates

*February 8, 2017*

**math**

sin(0) = 0 ... sin(90) = 1 so ... sin(50) > sin(40) cos(0) = 1 ... cos(90) = 0

*February 8, 2017*

**Chemistry**

there are 1000 L in a cubic metre so the density is 3000 g/L the molar mass is 44.956 g so one L contains ... 3000 / 44.956 moles the number of unit cells is half the number of atoms the volume is ... 1 L / [(3000 / 44.956) * 6.02E23 / 2]

*February 8, 2017*

**math**

d = 3 q 10 d + 25 q = 385 solve the system using substitution or elimination

*February 8, 2017*

**Further Mathematics**

11th term is 10 cr from 1st term 7 * 3^10

*February 8, 2017*

**Math**

-5 = -a + b - c y' = 3a x^2 + 2b x + c ... 4 = 3a - 2b + c y" = 6a x + 2b ... 0 = -6a + 2b 3 equations, 3 unknowns ... solve the system

*February 8, 2017*

**mATH**

520 X [1 + (0.04/12)]^60 IS THIS RIGHT WAY TO DO THIS just clarifying

*February 8, 2017*

**Physics**

150 kN to pull 12 cars to pull one car ... 150/12 kN

*February 8, 2017*

**physics**

momentum is conserved (75 * 2) + (50 * v) = 0

*February 8, 2017*

**Math**

x * x * (x - 3) * (x + 1)

*February 7, 2017*

**Chem**

reacts with water to form sulfuric acid this is the "acid rain" reaction

*February 7, 2017*

**Math**

it's an even power regardless of the sign of x, f(x) will always be positive

*February 7, 2017*

**Math**

h + c = 160 ... 200 h + 200 c = 200 * 160 500 h + 200 c = 369 * 160 subtract equations to eliminate c solve for h, then substitute back to find c

*February 7, 2017*

**Mathematics**

the area of the bottom of the box is ... 3456 / 6 = 576 (x + 12) [(576 / x) + 12] = 1500 x is one dimension, 576/x is the other

*February 6, 2017*

**Physics**

800 N * 20 m = 16000 J per second means 16 kilowatts

*February 6, 2017*

**Math**

h(g(x)) = 9 - (x + 3)^2 ... = -x^2 - 6x the max is on the axis of symmetry ... x = -b / 2a = 6 / -2 = -3 plug in -3 to find the maximum

*February 6, 2017*

**science**

v = mass/density = 2.4 kg / 2.70 g/cm^3 2.4 is only 2 sig fig

*February 6, 2017*