Friday

January 20, 2017
Total # Posts: 1,636

**Algebra 2**

use the quadratic formula to find the value(s) of x

*November 2, 2016*

**physics**

momentum is conserved (1200 * 14) + (2000 * 25) = ... (1200 + 2000) * v

*November 2, 2016*

**Chemistry**

8 half-lives 625 * (1/2)^8

*November 2, 2016*

**Chemistry**

3 half-lives m * (1/2)^3 = 6

*November 2, 2016*

**Chemistry**

2 days (48 hr) is 8 half-lives 10.0 * (1/2)^8

*November 2, 2016*

**Chemistry**

5 / 20 = 1/4 = (1/2)^2 2 half-lives

*November 2, 2016*

**Algebra 2**

3 half-lives 345 * 1/2 * 1/2 * 1/2

*November 2, 2016*

**Need help with math**

people who own both (b) will be counted in both groups (laptop owners and desktop owners) when you count all of the households, the "both" group is only counted once 130 + 30 + 50 + b = 250

*November 1, 2016*

**Mathematics**

the area is side times altitude 30 * 15 = 25 * x

*November 1, 2016*

**Math**

8 oz per cup

*October 31, 2016*

**Science**

switching the electrical polarity also switches the magnetic polarity

*October 31, 2016*

**Science 7**

switching the wires changes the magnetic polarity of the coil

*October 31, 2016*

**algebra 2**

3000 = 2000 [1 + (.038 / 2)]^(2t) ... t is the number of years 1.5 = 1.019^(2t) log(1.5) = 2t * log(1.019)

*October 31, 2016*

**Physics**

the gravitational potential energy becomes work driving the pipe m g h = f d 450 * g * 1.5 = f * .45

*October 30, 2016*

**Math**

y^2 + 5y - 6 = y^2 - 5y + 6 + 8 5y + 5y = 6 + 8 + 6

*October 30, 2016*

**Math**

(x + 2)^2 - x^2 = 44 x^2 + 4x + 4 - x^2 = 44 4x + 4 = 44

*October 30, 2016*

**Math**

28x - 7y = -119 ... add to 1st eqn

*October 30, 2016*

**math**

draw a Venn diagram of three intersecting circles enclosed in a box label the circles S, F, and G S/F/G -- 2 ... these are in all the two way intersections S/F -- 10 + (2) S/G -- 4 + (2) F/G -- 6 + (2) S -- 19 + (2) + (10) + (4) F -- 13 + (2) + (10) + (6) G -- 10 + (2) + (4...

*October 30, 2016*

**Math**

A = 3M A - 3 = 4 (M - 3) = 4M - 12 3M = 4M - 9

*October 30, 2016*

**Math**

18 r^5 = 2/27 9 r^5 = 1/27 r^5 = 3^-3 / 3^2 = 3^-5

*October 30, 2016*

**Math Grade 9**

square rooting implies that the yard is square ... from the result of your answer, this is not the case the "perimeter" in this problem, is only three sides A = L * W = 50 P = L + 2W a good investigation might consist of a table comparing L, W, and P ... remember, ...

*October 30, 2016*

**Algebra**

p + r = 18 35p + 49r = 728 solve the system by substitution or elimination

*October 30, 2016*

**math**

10 is a factor ... ?????0 The hundred thousands and ten thousands digit are the same and are odd ... must be less than 3, and odd ... 11???0 The sum of the hundreds and the thousands digits is 10 ... neither one can be zero The tens digit is a cube number and is one more than ...

*October 29, 2016*

**Physics**

the blocks accelerate at ... 60/18 = 10/3 m/s^2 the force necessary for b ... 15 * 10/3

*October 27, 2016*

**Science**

you think right

*October 26, 2016*

**College Calculus**

the max height is on the axis of symmetry of the parabola ... t = -b / 2a ... -96 / (2 * -16) ... plug into the equation to find s velocity is ds/dt ... solve for t when s is zero ... plug into the 1st derivative of s(t)

*October 26, 2016*

**math**

24 / 5 m = 30 / x m 24 x = 150

*October 26, 2016*

**Math/7th**

3 / 2 = 14 / x 3x = 28 x = 28/3 = 9 min 20 sec

*October 25, 2016*

**physics**

900 watts is 900 joules per sec 5 min is 300 sec 900 * 300 = 270 kJ

*October 25, 2016*

**Physics**

the car goes through a quarter of a circle in 10 s, at a speed of 15 m/s so the circumference of the circle is ... 10 * 15 * 4 = 600 m ... the radius is ... 600 / 2π the centripetal force (which causes the car to travel in a curved path) is ... m v^2 / r when the car is ...

*October 25, 2016*

**Science/Physics**

n = c / (.612 c) = 1 / .612

*October 25, 2016*

**algebra**

p = 94 e^(.06 * 4)

*October 24, 2016*

**Math**

suppose that 8 of Maggie's hours coincided with Gina's 8 hours that would complete 1/3 (8/24) of the project Maggie then finishes the remaining 2/3 in 22 hours (30 - 8) so Maggie would take 33 hours alone ... she does 24/33 or 8/11 working 24 hours with Gina Gina does ...

*October 24, 2016*

**math**

3S + 10 = 2L 2S + 2L = 100 3S + 10 = 100 - 2S 5S = 90

*October 24, 2016*

**math**

S + L = 50

*October 24, 2016*

**Physics**

a = 75/360 * π * r^2 da/dt = 75/360 * π * 2r dr/dt da/dt = 75/360 * π * 2 * 6 * 0.3

*October 24, 2016*

**math please help**

42 / (r + 6) = 10 / r 42 r = 10r + 60

*October 24, 2016*

**math please help**

p = f + 8 310 / p = 270 / f ... 310 f = 270 p 310 f = 270 (f + 8) 310 f = 270 f + (8 * 270) 40 f = 8 * 270

*October 24, 2016*

**physics**

1/2 m v^2 = m g h v = √(2 * 9.8 * 1.2)

*October 24, 2016*

**Math**

looking at a polar cross section Monica's radius of rotation (r) is ... 3960 mi * sin(90 - 13) her speed is ... 2 * π * r / 24 hr

*October 24, 2016*

**Math**

one half of TWO fifths is ONE fifth 1/5 * 60 =

*October 24, 2016*

**algbebra**

cd = 1 / (5 - 2) = 1/3 t = f + 6 cd t = 2f + 3 = f + 2 ... 4th = -1 ... 1st = -1 - (3 * 1/3) = -2 ... 25th = -2 + (24 / 3) = 6 s = (-2 + 6) * (25/2)

*October 24, 2016*

**algebra**

f(x) = -1 (3x + 8)^2 the graph is tangent to the x-axis ... at (-8/3,0)

*October 24, 2016*

**physics**

v^2 = .20 m * 9.8 m/s^2 this is the tangential velocity (v) divide by the radius to find angular

*October 23, 2016*

**Physics**

two forces on the ball ... tension and gravity gravity equals the vertical component of tension centripetal force is the horizontal component m v^2 / [1.75 sin(78.0º)] = ... m g tan(78.0º)

*October 23, 2016*

**Pure Math**

(x + yi)^2 = x^2 + 2xyi - y^2 x^2 - y^2 = -5 x y = 6 i would suggest a graphical solution ... try fooplot u = 2 + 3i

*October 23, 2016*

**physics**

d = 1/2 * a * t^2

*October 23, 2016*

**Maths GRE**

TOTAL price ... 3200 + 1800 % options ... 1800 / (3200 + 1800) * 100%

*October 23, 2016*

**Algebra**

because of the absolute value ... 2x-8 = 18 ... AND ... 2x-8 = -18

*October 23, 2016*

**Phyics**

the centripetal force is ... 42/56 g v^2 / 250 m = 42/56 * 9.8 m/s^2 this is the tangential velocity if you want rpm, multiply by 60 (sec to min); and divide by the station circumference

*October 23, 2016*

**math**

d = 1/2 a t^2 = 1/2 * 2.14 * 1.79^2

*October 23, 2016*

**physics**

the mass is not a factor (8.5 * r)^2 / r = .89 g r = .89 g / (8.5^2)

*October 23, 2016*

**Physics**

momentum is conserved in both the x and y directions the initial momentum is all in the x direction -- the moving ball PMy = 3.0 m/s * sin(60º) * 1.2 kg BVy = PMy / 7.2 PMx = 3.0 m/s * cos(60º) * 1.2 kg BVx = 3.5 - (PMx / 7.2) use Pythagoras to find BV

*October 22, 2016*

**Physics**

M1V1 = M2V2 ... M1^2 V1^2 = M2^2 V2^2 5 M1 V1^2 = 4 M2 V2^2 5 M1^2 V1^2 / M1 = 4 M2^2 V2^2 / M2 5 / M1 = 4 / M2 M2 / M1 = 4 / 5

*October 21, 2016*

**Precalc**

Ac = c^2 / 4 π triangle perimeter = Pt = 100 - c At = [Pt / (2 + √2)]^2 / 2 ... = (Pt)^2 / (12 + 8√2) ... = (1E4 - 200 c + c^2) / (12 + 8√2) A = (c^2 / 4π) + ... [(1E4 - 200 c + c^2) / (12 + 8√2)] the minimum A lies on the axis of symmetry...

*October 21, 2016*

**algebra**

x y = 6 * 3 = 18 2 y = 18

*October 21, 2016*

**math**

divide 2nd by -2 ... x = 103 + 5y subtract 5y ... x - 5y = 103 they are the same line

*October 21, 2016*

**science**

the speed of sound in air is ... 375 yd/s (approx) the speed of light is relatively instantaneous 3 * 375 = ?

*October 21, 2016*

**physics**

a) 15.9 / g = 15.9 m/s / 9.8 m/s^2 c) time up equals time down ... twice a) e) time from c) times 18.0 m/s

*October 21, 2016*

**Math**

the one with the exponent between the two

*October 21, 2016*

**Math**

let a = 22 / kg, and b = 12 / kg a + b = 20 kg 22a + 12b = 15 * 20 12a + 12b = 240 10a = 60

*October 21, 2016*

**math**

b / 12 = 75 / b b^2 = 900

*October 20, 2016*

**chemistry**

the two reactants react in equal amounts to give two products in equal amounts let x = concentration of each product Kc = 0.85 = [x]^2 / [1.00 - x]^2 .85 - 1.7 x + .85 x^2 = x^2 .15 x^2 + 1.7 x - .85 = 0 use quadratic formula to find x moles = concentration * vessel size

*October 20, 2016*

**Precal**

10^-2 = 3x + 5 -4.99 = 3x

*October 20, 2016*

**algebra**

200 (1 + .20)^3

*October 20, 2016*

**physics**

the weight is not a factor 1/2 m v^2 = m g h v = √(7 g)

*October 20, 2016*

**Algebra**

3.3E10 = 4.069E6 (1 +.026)^y log(3.3E4 / 4.069) = y log(1.026)

*October 20, 2016*

**Science**

the volume of water is ... π * 12^2 * 3 m^3 a cubic meter (m^3) of water has a mass of 1000 kg (a metric ton) the weight is the mass multiplied by the gravitational acceleration ... g = 9.8 m/s^2 the weight is in Newtons -- a unit of force

*October 19, 2016*

**physics**

s.h. = 4186 4186 * 2 * 75 = 627900 rounding or sig fig?

*October 19, 2016*

**algebra**

3^3 * (a^2)^3 = 27 a^6

*October 19, 2016*

**physics**

momentum is conserved the speed is zero

*October 19, 2016*

**physics**

the mass is not a factor horizontal speed = Sh = S cos(54.5) the flight time to the basket is ... 10.4 m / Sh = 10.4 * cos(54.5) / S vertical speed = Sv = S sin(54.5) gravity slows the vertical speed to zero at the peak, halfway through the flight Sv / g = 1/2 * 10.4 / Sh S...

*October 19, 2016*

**math**

(1.05^7 - 1) * 100%

*October 19, 2016*

**math**

a. 4000 = A [1+(.104 / 365)^(11 * 365) b. 4000 = A e^(.104 * 11)

*October 19, 2016*

**physics**

a) after 1 s the vertical velocity is 2 m/s ... so the average velocity is 7 m/s for the 1st sec b) similar to a) ... the object reaches its peak after 1.2 s ... the average velocity is 6 m/s c) time up equals time down ... 1.2 + 1.2

*October 19, 2016*

**physics**

time up equals time down h = 1/2 g t^2 = 4.9 m/s^2 * (2 s)^2

*October 19, 2016*

**physics**

60 = 1/2 k x^2 x = √(120 / 460)

*October 18, 2016*

**physics**

1/2 k x^2 = 1/2 m v^2 k = m v^2 / 4.5^2 convert 60 km/hr to m/s and calculate

*October 18, 2016*

**Arithmetic progression**

10 is not correct ... the 10th term is 23 the difference between terms is 2 27 is (5 + 22) ... the 1st term plus 11 differences ... 27 is the 12th term

*October 18, 2016*

**math**

57 (60 - 3) are M, E, or ME ... E + M + ME = 57 ... E + M = 48 M + ME = 2 (E + ME) ... M + 9 = 2E + 18 ... M = 2E + 9 substituting ... E + 2E + 9 = 48 ... E = 13 (i) M + ME (ii) E + ME (iii) M (iv) E

*October 18, 2016*

**Physics**

he has a constant velocity (zero acceleration) so the net force on him is zero the frictional force must equal his weight

*October 18, 2016*

**algebra**

(4y + 1i)(4y - 1i)

*October 18, 2016*

**Physics**

if his last turn is to the south he will be 70 m S and 12 m W of his starting position use Pythagoras to find the displacement

*October 18, 2016*

**GENERAL PHYSICS**

100 * 2π / 60 / 2 sec

*October 18, 2016*

**math**

36 / 47 = x / 120

*October 18, 2016*

**Chemistry**

mole = 6.02E23 particles 5.43E24 / 6.02E23

*October 18, 2016*

**math help**

1/2 * b * h = 10 b = h + 1 substituting ... h^2 + h - 20 = 0 (h + 5)(h - 4) = 0 h - 4 = 0

*October 18, 2016*

**Physics**

A) 2 * 7 * 10 N to the left B) 2 * 1/2 * 10 * 7^2 J C) the PE from B is converted to KE ... v = √[2 * B / m]

*October 18, 2016*

**math**

a = 2 pt, b = 4 pt, c = 5 pt a + b + c = 28 2a + 4b + 5c = 100 a = 2c 2a + 2b + 2c = 56 ... substituting ... 3a + 2b = 56 4a + 8b + 10c = 200 ... substituting ... 9a + 8b = 200 subtract the equations (after multiplying) to eliminate b

*October 18, 2016*

**Physics**

a faster stop (because concrete is hard) means a greater impulse

*October 18, 2016*

**physics**

the ball's speed is being converted to gravitational potential energy 1/2 m 6.4^2 = ... m g (2.2 - 1.5) + 1/2 m v^2 6.4^2 = 1.4 g + v^2

*October 17, 2016*

**Math**

s + b + w = 42 s = 4b 3s + 2b + 1.5w = 102 substituting ... 5b + w = 42 ... 14b + 1.5w = 102

*October 16, 2016*

**Math**

2 ft^3 = 2 * 12 * 12 * 12 in^3 24 * 144 / 231

*October 16, 2016*

**phy 101**

momentum is conserved so they "trade" velocities

*October 16, 2016*

**Math**

64, 32, 16, 8, 4, 2, 1, 1/2

*October 16, 2016*

**Physics**

a. weight = mass * g b. normal force equals weight ... but in opposite direction c. Newton's 2nd law ... f = m a ... in this case ... a = f / m d. correct

*October 16, 2016*

**Chemistry**

molar mass of acetone ... 58.08 g moles of acetone ... 1.920 / 58.08 molar enthalpy is energy per mole

*October 15, 2016*

**Physical science**

(A) m g h = 15 m g (B) m g h = 1/2 m v^2 ... v = √(2 g h) = √(30 g)

*October 15, 2016*

**Math**

it takes 12 min (the LCM of the numbers) divide by their rates to find the number of laps

*October 15, 2016*

**Math 1105**

yes

*October 14, 2016*