Monday

October 24, 2016
Total # Posts: 45,208

**Math**

as long as each x value appears only once, it is probably a function. So, I'd pick A and B on that basis. D also works. While 0 appears twice as the first element, the 2nd element is the same. So, the pair (0,3) appears twice, but it does not violate the rules for functions.

*September 8, 2016*

**Math**

8 + 6/2 = 11

*September 8, 2016*

**math**

v = at so, how long does it take to fall 685 ft?

*September 8, 2016*

**Math**

not sure what each watermelon with 12.73 inches and 2.7 inches in height means

*September 8, 2016*

**Algebra**

3*84 <= 81+87+x <= 3*89 254 <= 168+x <= 267 ...

*September 8, 2016*

**Algebra**

since distance = speed * time, 20x = (20-4)x + 6 and I think you meant "downwind"

*September 8, 2016*

**Math**

correct. If you type in your expressions at wolframalpha.com you can check your answers quickly. For example, http://www.wolframalpha.com/input/?i=2+1%2F7+divided+by+3+2%2F3

*September 8, 2016*

**math**

That's h of x, not h times x. h(x) = √(4-x^2)/(x-3) or h(x) = √((4-x^2)/(x-3)) In either case, x=3 is excluded because the denominator is zero. Now, √z has a domain of z>=0. In the first case, 4-x^2 >= 0, so x^2 <= 4 |x| <= 2 In the second ...

*September 8, 2016*

**Maths**

roughly 0.6 * 150

*September 8, 2016*

**Algebra 2**

15000/3500 = ? round up to next whole bucket

*September 8, 2016*

**Technology**

correct

*September 8, 2016*

**Math**

just write down the parts and add them up

*September 8, 2016*

**Algebra**

well, 7^2 = 49 8^2 = 64 So, it's either 7 or 8, but now you gotta figure which one.

*September 8, 2016*

**Math**

oh, well, 1 3/7 = 1+3/7 = 7/7 + 3/7 = 10/7

*September 8, 2016*

**Math**

well, the idea is right, but 3/7 = 15/35 Then, do just what you did with the previous problem: 15/35 - 38/35 = -23/35 Plus, you misspelled "to"

*September 8, 2016*

**math**

yes.

*September 8, 2016*

**math**

huh? This is exactly like the last one; just use different numbers. What do you get?

*September 8, 2016*

**math**

c = t+60 t = 2/3 c or, t = 2/3 (t+60)

*September 8, 2016*

**Math**

hey, it's nice to see a problem posted that shows some thought and effort.

*September 8, 2016*

**Math**

for sphere, v = 4π/3 r^3 for cylinder, v = πr^2h so, since the radius of the cylinder is 1, 4π/3 (1^3+2^3) = πh

*September 8, 2016*

**Math**

draw a diagram. The diagonal of the square is the diameter of the circle. Knowing that, you can figure the area of the square.

*September 8, 2016*

**science**

#1 Really, lattices are found in crystals. (Plus, why would that be affected by a charged balloon?) #2 C looks good to me.

*September 8, 2016*

**Math**

google is your friend. just search for equilateral triangle. If the side is s, then perimeter = 3s area = √3/4 s^2

*September 8, 2016*

**Mathematics**

(3 5/7)x = 3 1/4 (26/7)x = 13/4 x = 13/4 * 7/26 = 13/26 * 7/4 = 1/2 * 7/4 = 7/8

*September 8, 2016*

**Math**

total points for 4 tests @ 96 = 384 points so far: 94+98+98 so, how many does he need on the last exam? Hint: 96 is the average of 94 and 98

*September 8, 2016*

**Science**

a magnet will get the iron oil floats on water evaporate the water to get salt

*September 8, 2016*

**physics**

The larger car is the Mercedes-Benz.

*September 8, 2016*

**Maths**

Drop altitudes from C and D. That will create a rectangle and two right triangles. I'm sure you can find those areas. Don't forget the Pythagorean Theorem to find the altitude.

*September 8, 2016*

**Algebra2**

Draw the lines y = 4x-1 y = 3x-1 Shade everything below the 1st, and above the 2nd. The intersection of the two shaded areas is the solution set

*September 8, 2016*

**Algebra2**

Solve the inequalities by graphing y<=4x-1 y>3x-1

*September 8, 2016*

**Math**

2/3 X 21 2 x 7 14

*September 8, 2016*

**AAHHOOOOGAH! Homework Dump!**

how about showing some of your ideas on any one of the problems?

*September 8, 2016*

**Math**

how can a rectangle have three such ratios? If 3:4, then the width is 3x and the length is 4x, and we have 2(3x+4x) = 70

*September 8, 2016*

**Calculus**

Riemann sums, trapezoidal method. google numerical integration or quadrature

*September 8, 2016*

**Calculus**

I don't see any way, other than numerical approximations. The velocity is not a nice linear function, so only an integral can give an exact answer ∫[0,14] (11+6cosx) dx

*September 8, 2016*

**MATHS**

dC/dx = 600 - 180000/x^2 plug in x=100 I assume C(x) is the income function

*September 8, 2016*

**math**

ummm, 33*41 ?

*September 7, 2016*

**Math**

You have the right idea re add 6.75 + 3.5 = 10.25 not 10.35 you have the right process to get per hr $92.25/10.25 =$9 per hr

*September 7, 2016*

**Pre algebra**

a rational number is what you know as a fraction. It is the ratio of two whole numbers. 3/4, -7/11, etc. An integer is a rational number with a denominator of 1. Or, more commonly just what you think of as a counting number, but may be negative: 3/1 = 3 -2/1 = -2 and so on An ...

*September 7, 2016*

**math**

(1/20000)^2 * 50 km^2

*September 7, 2016*

**Math**

You have 8 3.4 gal of paint you're going to use 2/5 of it to paint what type of math would you use to figure how much? Multiplication!! 8 3/4 times 2/5 = see if you can get it from there

*September 7, 2016*

**MATH...please help**

If $x is at 5%, then the rest (10000-x) is at 6%. The interest of both parts must add up to 575: .05x + .06(1000-x) = 575

*September 7, 2016*

**Algebra HELP!**

when it says substitution, use the value from one equation to solve the other. y = 2x-1, so the 2nd equation becomes 2x+2(2x-1) = 22 2x + 4x - 2 = 22 6x = 24 x = 4 Using elimination, find ways to make one variable disappear by adding the two equations (or multiples of them) 5x...

*September 7, 2016*

**Advance Math**

well, 45° is 1/8 of a circle. So, the volume is 1/8 of the whole.

*September 7, 2016*

**Math**

If the fraction is x/(x+1), then we are told (x+1)/x = 3/4 + 7/12

*September 7, 2016*

**Algebra ll**

well, what is the minimum number of tellers?

*September 7, 2016*

**Calculus integrals**

there are nice online Riemann sum calculators so you can check your work >wink wink<

*September 7, 2016*

**Math**

hundreds

*September 7, 2016*

**math**

seven times a number: 7x difference between 18 and 7x: 18-7x Think you can take it from there?

*September 7, 2016*

**Calculus**

I'm sure you can make the table. You know that sinu/u -> 1 as u ->0 since cos(0) = 1, that means that tanu/u -> 1 as u -> 0 You have tan3x/7x = tan3x / (3x)*(7/3) = (tan3x/3x) * 3/7 so, what do you think the limit is?

*September 7, 2016*

**Math**

assuming that "t" means "+", 4a+a+a = 4a + 1a + 1a = (4+1+1)a = 6a the a's add up just as 4 oranges + 1 orange + 1 orange = 6 oranges 4+1+1 of anything make 6 of that thing. In this case, "a"

*September 7, 2016*

**Math - vectors**

LCM(4,14) = 28 So, 7r = 28i + 7tj 2s = 28i - 24j so, if 7t = -24, 2s = 7r, so one is a multiple of the other. Or, more directly, 14/4 r = 14i + 14/4 t j so, if 14/4 t = -12, s is a multiple of r.

*September 7, 2016*

**Science**

you know that gravity provides constant acceleration. That means the the velocity grows by the same amount in equal time periods. That is why g = 9.8 m/s^2 That means g = (9.8m/s)/s Or, v grows by 9.8 m/s every second. So, if v=9.8t after t seconds, then you want t where 9.8t...

*September 7, 2016*

**Math**

naturally, (2x+7)^3 just expand that out.

*September 7, 2016*

**Math III Honors**

note that at each break point, the base amount is the maximum tax of the previous bracket. That means that for income <= 6000 max tax is 600 <= 27950 max tax is 3892 <= 67700 max tax is 3892.50 So, tax of 4446 means that income was between 27950 and 67700 3892 + .27(x...

*September 7, 2016*

**Math**

pairs where y=0 are on the x-axis pairs with x=0 lie on the y-axis

*September 7, 2016*

**Math**

if his age now is x, then Four more than twice Jason's age is 2x+4 now do the other, set them equal, and find x.

*September 7, 2016*

**6th grade plz help**

"more than" means you add 4+2 is 2 more than 4 so, now what do you think is 15 more than d?

*September 7, 2016*

**Algebra**

It's not very clear just what you have...

*September 7, 2016*

**Maths - Bogus**

do as with all inductions. show that it's true for n=1 sinx = sin^2(x)/sin3x Nope, not true. So, how about n=2? sinx+sin3x = sin^2(2x)/sin3x Nope. Better fix this and come back.

*September 7, 2016*

**Geometry**

It has to do with so-called addition property of equality and division property of equality. Basically, if two things are equal, adding or dividing both things by the same amount does not affect their equality.

*September 7, 2016*

**math**

after x hours after 2PM, you want 500x + 550(x-2) = 3100

*September 7, 2016*

**geometry**

if every dimension, including the height is doubled, then the area grows by a factor of 4.

*September 7, 2016*

**Math, Calc**

x^2+2xy+4y^2=12 2x + 2y + 2xy' + 8yy' = 0 (x+4y)y' = -x-y y' = -(x+y)/(x+4y) at (2,1) y' = -1/2 so, the line is y-1 = -1/2 (x-2)

*September 7, 2016*

**Math (urgent)**

Looks good to me

*September 7, 2016*

**Math (urgent)**

well, do the sub: x^2 + (x-1)^2 = 25 or, even without doing the math, you can see that none of the choices satisfies y=x-1 for both points But (d) is also wrong, since the line crosses at (-3,-4) and (4,3) I suspect at least one typo.

*September 7, 2016*

**maths**

m = [-5±√(5^2+4*2*20)]/4

*September 7, 2016*

**Math**

the time taken by the tortoise is t seconds So, the time used by the hare for running is t-120 seconds The tortoise ran 0.2m farther, so since distance = speed * time, 0.1t = 2(t-120)+0.2 Now just solve for t, and then you can get the distance.

*September 7, 2016*

**algebra**

x > 45000

*September 7, 2016*

**math**

5/12 + (3/7)(7/12) = 5/12 + 3/12 = 2/3 So, 1/3 of the original amount = 856

*September 7, 2016*

**math**

If z = x+yi and a = c+di then zz¯ = (x+yi)(x-yi) = x^2+y^2 a¯z = (c-di)(x+yi) = (cx+dy)+(cy-dx)i az¯ = (c+di)(x-yi) = (cx+dy)+(dx-cy)i so, adding all that up you get x^2+y^2 + 2cx+2dy + b = 0 (x+c)^2 + (y+d)^2 = c^2+d^2-b Looks like a circle to me.

*September 7, 2016*

**Maths Graph**

http://www.wolframalpha.com/input/?i=plot+y%3Dx%5E2+for+x+%3D+0..4

*September 7, 2016*

**math**

why keep posting the same problem over and over? You know, it just may be that no one is awake in the middle of the night. Surely by now you could have drawn a diagram and seen that if the 2nd elevation was taken at distance x, and the height is h, then h cot35° - h cot55&...

*September 7, 2016*

**math**

x+y+z = 95 2x = 4y 2x = 5z 50,25,20

*September 7, 2016*

**Algebra Word promblems**

a. correct b. the final salary is less because after the 5% cut ($2500), a 5% raise is less than $2500, since the base salary amount is now less.

*September 7, 2016*

**College Algebra**

if it is horizontal, then y never changes. So, what is y at that point?

*September 7, 2016*

**College Algebra**

if it is vertical, then x does not change. So, what is x at that point?

*September 7, 2016*

**Physics**

1. 60+40 km 2. 100km/1.5hr = 100/1.5 km/hr

*September 7, 2016*

**Math College 115**

If a is in years, then you know that when a=0, w=3.8 So, w = 3.8 + ma Now, what is m? It is the change in w divided by the change in a: 37.0/2 = 18.5 w = 3.8 + 18.5a

*September 6, 2016*

**math**

well, 400,000,000+30,000,000 = 430,000,000 add the others similarly.

*September 6, 2016*

**Physics**

25mi/hr * 1hr/3600s * 1609m/mi = 25*1609/3600 m/s

*September 6, 2016*

**Algebra I need help**

google is your friend.

*September 6, 2016*

**Algebra - Reiny is right**

Oops. I misread the problem.

*September 6, 2016*

**Algebra**

you want w when 900+10w = 500+15w

*September 6, 2016*

**physics**

You sure are cagey with the names of your vectors. I'll call them u,v,w. Just draw a diagram. It should be clear that the x- and y-components of vector u are x: -113 cos34° y: 113 sin34° Do the others the same way. For magnitudes, recall that |<x,y>| = √...

*September 6, 2016*

**science**

many discussions found via https://www.google.com/#q=electric+field+at+center+of+circular+arc

*September 6, 2016*

**Math Please Help Me**

just think about it. How much clay was used? 1 1/2 + 3/4 = 1 2/4 + 3/4 = 1 5/4 = 9/4 lbs Now, if each student uses 1/8 lb, the 1 whole pound is enough for 8 students, right? So 8 * 9/4 = 72/4 = 18 students can be satisfied. Or, since 1/4 lb = 2/8 lb, each 1/4 lb of clay will ...

*September 6, 2016*

**algebra 2**

Mary has a 2-hr start, so she's 120 mi ahead at 8 am. Tom hoes 10 mi/hr faster, so how long will it take him to make up the 120 mi?

*September 6, 2016*

**maths**

wow - can you make heads or tails of that gibberish? I assume that 22-60 means 22°60'. No idea what "tita" means. Must be "theta". At any rate, since the circumference of the earth is about 40,000 km, the plane flew 8000km = 1/5 of the way around ...

*September 6, 2016*

**Math**

just think about it. How much clay was used? 1 1/2 + 3/4 = 1 2/4 + 3/4 = 1 5/4 = 9/4 lbs Now, if each student uses 1/8 lb, the 1 whole pound is enough for 8 students, right? So 8 * 9/4 = 72/4 = 18 students can be satisfied. Or, since 1/4 lb = 2/8 lb, each 1/4 lb of clay will ...

*September 6, 2016*

**Math**

rate per hour is #dollars / #hours (1 1/2 + 3/4)/(1/8) or 8 * (3/2 + 3/4) = ?

*September 6, 2016*

**Math**

uh, -12/1

*September 6, 2016*

**Algebra1**

#1 D is correct #4 B is correct, but the rate of change of f is 2/3, and of g is -3/4 #10 A is correct #1 I agree. Must be a typo. f(1)+g(2) = 4, however #2 C is correct

*September 6, 2016*

**math**

start with volume = mass/density find the density of each liquid, and you can figure the volume. Then volume = arae * height You know the area of the liquid cross-section, so once you know the total volume, the height is height = volume/area

*September 6, 2016*

**Technology**

seems to me that R T G V F are done with the left index finger

*September 6, 2016*

**Math**

Huh? 10+2.5x = 25 2.5x = 15 ...

*September 6, 2016*

**Math**

After x years, the height y is y = 10 + 2.5x So, find x when y=25

*September 6, 2016*

**Math**

Ths distance of (x,y) from the y-axis is just x. So, √((x-2)^2 + (y-3)^2) = x (x-2)^2 + (y-3)^2 = x^2 x^2-4x+4 + (y-3)^2 = x^2 (y-3)^2 = 4x-4 (y-3)^2 = 4(x-1) as I showed using the properties of parabolas

*September 6, 2016*

**Math**

review the definition of a parabola. The standard equation is y^2 = 4px if the focus is at (p,0) and directrix x = -p So, you have to shift your axes giving you (y-3)^2 = 4(x-1) see http://www.wolframalpha.com/input/?i=parabola+(y-3)%5E2+%3D+4(x-1)

*September 6, 2016*