Saturday

October 22, 2016
Total # Posts: 45,134

**Math**

I have also seen this referring to 0.57 meaning a repeating decimal. In that case, 0.57 = 57/99 because if x = 0.57 100x = 57.57 now subtract and the .57 part goes away and you are left with 99x = 57

*October 17, 2016*

**Maths**

are you missing some parentheses?

*October 17, 2016*

**Math**

reposting after only 7 minutes? Impatient much? See your earlier psting.

*October 17, 2016*

**Math Help**

each year, 1/5 of lost value (10800-18000) is subtracted. Or, note that 18K is 1/6 of 108K. That is, in 5 years it has lost 5/6 of its value: 1/6 per year.

*October 17, 2016*

**Math**

express all fractions with a denominator of 6, and it becomes quite clear. Just look at the numerators.

*October 17, 2016*

**Algebra**

this site is a great help: http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html

*October 17, 2016*

**Math**

round down and round up

*October 17, 2016*

**MATH (Please Help)**

each year 1000,000/80 = 12500 is being subtracted. Sn, after n years the value will be 1,000,000 - 12500n Or, after 48 years, the remaining value will be 32/80 of its original worth.

*October 17, 2016*

**geometry b**

You have the points J...T...H (0,2)...(0,4) ...(x,y) Clearly (x,y) = (0,6)

*October 17, 2016*

**math**

draw your 8-15-17 right triangle and this becomes easy.

*October 17, 2016*

**math**

122 just evaluate in the right order.

*October 17, 2016*

**Linear equation**

f = m+25

*October 17, 2016*

**Math**

54:46 = 27:23

*October 17, 2016*

**math**

place all over a common denominator (63) to sort easily.

*October 17, 2016*

**statistics**

1-P(no heads) = 1-.45^4

*October 17, 2016*

**Physics**

Assuming the pebble missed the tree entirely, and fell onto level ground, the final downward speed is the same as the initial upward speed. 11 * sin75

*October 17, 2016*

**Math**

next step: 4-t = 3t-8 ...

*October 17, 2016*

**Physics**

the max height and time in air are the same as if the cat had left it alone. For the horizontal displacement, figure how long it takes to fall from the max height (1/2 the total air time). The extra displacement from the cat is the x-velocity * that time. The final velocity on...

*October 17, 2016*

**Arithemetic progression**

or, since the sum of the first n odd numbers is n^2, n^2 - 2^2 = 480 n^2 = 484 n = 22 The sum of the first 22 odd numbers is 484. Subtract the first 2, leaving 20, as above.

*October 17, 2016*

**Physics**

v = Vo + at s = Vo*t + 1/2 at^2 so, v = 0 + 3(10) + 2(-4) = 22 m/s s = (0*10 + 1/2 * 3 * 10^2) + (30*2 - 1/2 * 4 * 2^2) = 202 m

*October 17, 2016*

**Physics**

h = 1/2g (v sinθ)^2 v sinθ t - 4.9t^2 = 0 r = v^2/g sin2θ

*October 17, 2016*

**Physics**

just use your basic equations of motion: v = Vo + at s = Vo*t + 1/2 at^2 p = mv KE = 1/2 mv^2 momback if you get stuck. And say where.

*October 17, 2016*

**Math115**

the "half-life" is 25 years. (1/2)^(1/25) = 0.97265

*October 17, 2016*

**Maths compound interest**

42

*October 17, 2016*

**Maths**

Surely you mean either 2% per hour or doubling every 2 hours. That would make the population either 500,000 * 1.02^2 or 500,000 * 2^1

*October 17, 2016*

**math**

30/6 = 5, so 54/6 : 30/6 = 9:5

*October 17, 2016*

**MATH 115**

The linear model is ok, but the exponential growth is way off. It grew by a factor of 1.48 in 12 years, so g(t) = 100000 * 1.48^(t/12) Clearly you did not try your t=12 input in g(x) exponential functions are "never" b^(k/t) as t grows large, that approaches just 1.

*October 17, 2016*

**Math**

If x is the sort side, then x^2 + (2x-1)^2 = (2x+1)^2

*October 17, 2016*

**calculus**

I will assume that we are just measuring the inner boundary of the path. Thus, the two lengths L and a circle of radius r has perimeter p = 2L + 2πr The inner picnic area is a = L(2r) = (1000-πr)(2r) = 2000r - 2πr^2 da/dr = 2000 - 4πr da/dr=0 when r = 500...

*October 17, 2016*

**calculus**

wh = 80 a = (w+2)(h+2) = (w+2)(80/w + 2) = 2w + 84 + 160/w da/dw = 2 - 160/w^2 da/dw = 0 when w^2 = 80 so, as usual a square is your best bet.

*October 17, 2016*

**MATH**

the graph of a linear function is a straight line. Does y^2 define a straight line?

*October 17, 2016*

**Math**

1/5 = 5^-1 (1/5)^-m = 5^(-1 * -m) = 5^m So, now you have 5^m = 125^3m = 5^9m m = 9m m = 0

*October 17, 2016*

**Math**

hint 2: 125 = 5^3

*October 17, 2016*

**Math**

total points: 285 4*50 + 85 = 285 making more than 50 on any of the other 4 tests would reduce the highest score.

*October 17, 2016*

**math**

If there are x lbs of the 20% protein, then the rest (1200-x) is 10%. So, adding up the amounts of protein, it must equal the total: .20x + .10(1200-x) = .15(1200) Since 15% is halfway between 10% and 20%, expect the mix to be half and half.

*October 16, 2016*

**math**

70+90-x = 150-10

*October 16, 2016*

**Science**

a good start -- but to what?

*October 16, 2016*

**Math**

True. m1 = -a/b m2 = b/a

*October 16, 2016*

**Calculus**

looks good to me.

*October 16, 2016*

**Electronic Level Alarm?**

?

*October 16, 2016*

**Math**

3/8 of a gallon.

*October 16, 2016*

**algebra**

2(w + w+6) = 176

*October 16, 2016*

**Physics 11 URGENT STEVE OR BOB OR ANY PHYSICS Guys**

split the vector into components and add them up. Or, if you're tricky, you can treat the vectors as complex numbers and wolframalpha to do the work. The only trick is remembering that complex numbers measure counterclockwise from east, while headings measure clockwise ...

*October 16, 2016*

**Math**

s+b+w = 42 3s + 2b + 1.5w = 102.00 s = 4b now crank it out.

*October 16, 2016*

**maths**

If x take both, b+c-x = 60 b = c+6 2c+6-x = 60 2c-x = 54 So, unless you know something more, there are many possible solutions, such as x=0, b=33, c=27 x=2, b=34, c=28 ... x=52, b=59, c=53 x=54, b=60, c=54

*October 16, 2016*

**Math**

convert all to decimals; then it is much easier.

*October 16, 2016*

**Math**

V(x) = length*width*height = (12-2x)(20-2x)(x)

*October 16, 2016*

**math**

surely it is 18, since 6 divides 18.

*October 16, 2016*

**Math**

Depending on the constant of proportionality, 280+30x is always proportional to x. if x=1, 310 = 310x If x=2, 340 = 170x If x=3, 370 = 37/17 x and so on. Keep going till you find the constant you like.

*October 16, 2016*

**Geometry I**

if you need to fix a problem, don't repost the whole thing again. Just edit your original post. Wastes time checking all the redundant posts. Since the question specifies that there was an initial reflection, the only way to wind up with no reflection is to have a second ...

*October 16, 2016*

**Geometry I**

what the heck is y-^ ? All I see is a translation.

*October 16, 2016*

**Math**

come on. Add up all the stiff on the left and see what you need to arrive at -9. For example, if all those numbers add up to -6, you need another -3.

*October 16, 2016*

**Maths**

Since the coefficient of x^2 is 1, a=1. The point (-3,0) means that -3 is a root of the function. So, y = (x+3)(x-q) y(3) = -16, so (6)(3-q) = -16 3-q = -8/3 q = 17/3 Now we know that y = (x+3)(x-17/3) That fits any of the choices, given the proper value of a. I suspect that ...

*October 16, 2016*

**Math**

that's why they gave you the angle. 11/x = cos28° Surely this unit in your text talks about the basic trig functions. Maybe you should read it.

*October 16, 2016*

**Math**

all are correct. But online use parentheses to make things clear. You should have written for #1 (y-5)/3 because as written it means y - 5/3

*October 16, 2016*

**mathematics**

surely you can see that 60 is not an answer. There are only 40 students in all! Since 8 students take neither, there are only 32 students to worry about. If you count all the science and math, you get 50. But in doing that, you have counted twice the students who take both. ...

*October 16, 2016*

**mathematics**

so, did you make your diagram? By the way, in classes students do not offer the subjects.

*October 16, 2016*

**MATH**

x+y = 38 2x+8 = 5y This isn't Twitter; you can actually spell the words out. And how about that semicolon?

*October 16, 2016*

**Math**

since there is a common difference, 2x+1 - x = 5x-1 - (2x+1) Then just use your formula for S10

*October 16, 2016*

**Physics**

29 lb/ft^2 * (150*850)ft^2 = ? lb

*October 16, 2016*

**Algebra**

2n - (5+3) I think you have garbled the question, since there is no equation involved.

*October 16, 2016*

**maths**

well, the three angles add up to 180. Don't forget that an equilateral triangle is also isosceles...

*October 16, 2016*

**Math**

up or down? ... either way, multiply 1+.05 or 1-.05

*October 16, 2016*

**algebra**

If the number of general admissions is x, then the rest (948-x) were reserved. So, add up the receipts: 4.50x + 5.50(948-x) = 4588.00

*October 16, 2016*

**dinesh physics**

v = at plug and chug. the acceleration means that during each second, the speed increases by 2 m/s

*October 16, 2016*

**calculus**

f(s) = 15(s-65) for s>65 15(40-s) for s<45 or f(s) = 15|s-52.5| if |s-52.5| > 12.5 f(s) = 0 otherwise.

*October 16, 2016*

**Math (derivative by limit process)**

f(x+h)-f(x) = 1/√(x+h) - 1/√x = (√x - √(x+h))/√(x(x+h)) = (x-(x+h))/(√x(x+h))(√x+√(x+h)) = -h/(√x(x+h))(√x+√(x+h)) divide by h and you have -1/(√x(x+h))(√x+√(x+h)) as h->0, that is -1/(&#...

*October 16, 2016*

**distance problem**

since time = distance/speed, if his walking speed is x km/hr, 9/x = 17/(x+4) Now crank it out.

*October 16, 2016*

**calculus**

f(x) is constant. It does not matter what x is.

*October 16, 2016*

**Math**

his final location, relative to the starting point is (0,160) + (-150,0) + (-280cos65°,-280sin65°) Add up all the pairs and then just use the distance formula.

*October 16, 2016*

**Physics**

154 cos34°

*October 15, 2016*

**Calculus**

If all the powers are odd, f(x) is odd. If all even, f(x) is even. remember that constants are x^0, or even powers.

*October 15, 2016*

**Integrals calculus**

no. if u = x^2-8, du = 2x dx You need an x in the numerator. Instead, use partial fractions. x^2-8 = (x+√8)(x-√8) You will wind up with logs of those factors.

*October 15, 2016*

**Calculus @Matt**

all those words!! Why not just 2 <= x <= 3 or even better, [2,3]

*October 15, 2016*

**Adv functions**

f(x) = (ax+b)/(x+d) Since y=30 is the asymptote, a=30: f(x) = (30x+b)/(x+d) Now plug in your two points and solve for b,d.

*October 15, 2016*

**Functions - math**

1) You have two equations using f(-2) and f(-3): 4a^2+2a+3b = 4a^2-b+8 9a^2+3a+3b = 7a^2-b+14 Those reduce to a+2b = 4 2a^2+3a+4b = 14 Solve those and you get (a,b) = (3/2,5/4) or (-2,3) (2) a=1 b = -1 means f(x) = x^2-x+6 = (x - 1/2)^2 + 23/4 The range is y >= 23/4 so, f^-...

*October 15, 2016*

**Math**

If rectangle B has width x and length y, we have A/B = (x/3 * 2y)/xy = 2/3 just multiply the scale factors: 1/3 * 2 = 2/3

*October 15, 2016*

**Math**

the sum is 4*48 = 192 so, the other two numbers add to 62, making their average 31.

*October 15, 2016*

**Math**

24 = 2/3 * 36. So, multiply by 36, and you have 2/3:3/4 = 24:27 = 8:9 or, if you use a common denominator, 2/3 : 3/4 = 8/12 : 9/12 = 8:9

*October 15, 2016*

**math**

you have a 9-12-15 triangle.

*October 15, 2016*

**Math**

35+13 = 48

*October 15, 2016*

**math**

c=2v c-12 = v+12 + 10 2v-12 = v+22 v = 34 c = 68 ...

*October 15, 2016*

**Math**

assuming the rectangles are similar, if the lengths are in the ratio 1:3 then the areas will be in the ratio 1:3^2 = 1:9

*October 15, 2016*

**Trigonometry**

Recall the sum of angles for tan: tan(A-B) = (tanA-tanB)/(1+tanAtanB) You have the reciprocal of that, so what you have is cot(200-80) = cot(120) = -1/√3

*October 15, 2016*

**math**

recall that lim x->0 of sinx/x and tanx/x = 1 You have tan(3x^2)/x^2 + sin^2(5x)/x^2 = 3*tan(3x^2)/(3x^2) + 25(sin5x/5x)^2 --> 3+25 = 28

*October 15, 2016*

**math, science, algebra**

1000(1+.09/2)^(2*2) - 1000

*October 15, 2016*

**eng, math, science, geography**

original price: 2c sale price 1.2c discount: .8c/2c = 40%

*October 15, 2016*

**maths sequence**

take a look at the sums of powers of integers: 1+2+3+... = n(n-1)/2 (2nd degree) 1^2+2^2+3^2+... = n(n+1)(2n+1)/6 (3rd degree) 1^3+2^3+... = n^2(n+1)^2/4 (4th degree) The sum of kth powers of integers is a k+1 degree polynomial.

*October 15, 2016*

**maths sequence**

see related questions below.

*October 15, 2016*

**Pre-calculus**

2x-3y-6=0 has slope 2/3 x+5y-20=0 has slope -1/5 so, you want arctan(-1/5) = -11.3° arctan(2/3) = 33.7° so, the acute angle between the lines is 45°

*October 15, 2016*

**Fermats Little Theorem**

well, 512 mod 61 = 24 it's turtles all the way down.

*October 15, 2016*

**mathematics**

Recall Euler's formula: V+F-E=2 plug in your numbers and solve for F

*October 15, 2016*

**Math**

r^2 + h^2 = 36 so, h=√(36-r^2) v = π/3 r^2 √(36-r^2) dv/dt = 3r(24-r^2)/√(36-r^2) dr/dt So, plug in your numbers. max volume is when r^2 = 24

*October 15, 2016*

**Algebra**

1/2 F = 16 + 9/10 C F = 32 + 9/5 C

*October 15, 2016*

**Algebra**

x + 2x + 4x+1 = 36

*October 15, 2016*

**Maths**

see related questions below

*October 15, 2016*

**maths-sequence need help**

the growth does not appear exponential, yet it isn't just an easy power, either. Note that the terms are 2*1, 3*5, 4*13, 5*25, 6*41, ... The first factor is easy: (n+1) The second factor is the sequence 1, 5, 13, 25, 41 1st difference: 4,8,12,16, ... 2nd difference: 4,4,4...

*October 15, 2016*

**math**

b+g=42 3/4 b + 2/3 g = 30 g = 42-b, so 3/4 b + 2/3 (42-b) = 30 b = 24

*October 15, 2016*

**math**

11 * 0.98

*October 15, 2016*