Friday

September 30, 2016
Total # Posts: 44,247

**math**

(8 1/3 mi)/(3 3/4 hr) = (25/3 mi)/(15/4 hr) = (25/3)(4/15) mi/hr = 100/45 mi/hr

*September 30, 2016*

**math**

h = 7-9cos(-(x+1)) 9cos(-(x+1)) = 7-h cos(-(x+1)) = (7-h)/9 -(x+1) = arccos((7-h)/9) x+1 = -arccos((7-h)/9) x = -1-arccos((7-h)/9)

*September 29, 2016*

**Math**

16 dimes gives $160, but not enough coins. each dime replaced adds a coin (an extra nickel), so since we are 7 coins short, we need to replace 7 dimes with nickels: 9 dimes and 14 nickels

*September 29, 2016*

**math-8**

generally stuff we do in life ranges between 0.01 and 100 anything outside that range is better expressed with scientific notation.

*September 29, 2016*

**Math**

the shares are 2x,5x,7x, and 7x = 2x + 1180

*September 29, 2016*

**Math (Algebra II)**

consider the amount of anti-freeze present. If you replace x gallons with 100%, then the rest (80-x) is still 40%. .40(5-x) + 1.00x = .80*5

*September 29, 2016*

**algebra 1**

15(26-4) <= x <= 15(26+4)

*September 29, 2016*

**Math**

f(2) = 8-4-6 = -2 f(3) = 27-9-6 = 12 So, a root is between 2 and 3.

*September 29, 2016*

**Math**

well, there are 16 left...

*September 29, 2016*

**Algebra 1**

D is right.

*September 29, 2016*

**Physics- Acceleration**

a = (30m/s)/(12s) = 30/12 m/s^2 s = 1/2 at^2 = ...

*September 29, 2016*

**Math homework 📚**

m/n tells you how many times you can subtract n from m. Work out a long division problem. It is really just a guessing game; at each step you try to figure out how many times the divisor can be subtracted from the dividend.

*September 29, 2016*

**Algebra 1**

Not a very clear exposition. If two sides are 2x+1 and 3x-4 you have not provided enough information. Something else about the shape must be given, such as right triangle, isosceles or something else to allow calculation of the 3rd side. Now, with that in mind, show your</u...

*September 29, 2016*

**Math**

Actually, when rounding to the nearest tenth, it should be written 830.0 to indicate that tenths are being counted. So, with that in mind, what do you think?

*September 29, 2016*

**math**

example 1x28: 1x4 + 1x24 Now work through the other pairs of factors, using only those which allow splitting off a smaller rectangle.

*September 29, 2016*

**Math**

That's a good start, but there is border on both sides of the photo.

*September 29, 2016*

**Math**

how many animals? straight permutation formula

*September 29, 2016*

**math**

the commutative property says that you can switch the order of addition. So, 1+2+3+4=10 2+1+4+3=10 while the property only applies to two numbers, by using it over and over, you can completely shuffle the addends any way you like.

*September 29, 2016*

**Math**

well, what is the 1st? the 2nd? see a pattern there?

*September 29, 2016*

**Math**

p = 6f now write the other facts as algebra, and then solve the equations.

*September 29, 2016*

**math**

how-many 2-page groups? Each takes 3 minutes. So: (268/2)*3

*September 29, 2016*

**math**

so, if x is the number, what is the sum of the number and three? That's the first step. Then keep going. If you get stuck, come back with what you got so far.

*September 29, 2016*

**Math**

for large values of 1, 1+1=3, for small values of 3.

*September 29, 2016*

**math**

an addition problem. This is a test posting, right? Or maybe a spelling problem ...

*September 29, 2016*

**math**

35 km/hr * 1000m/km * 1hr/3600s = ? m/s

*September 29, 2016*

**algebra**

since distance = speed * time, if the outbound speed was x, then 2x = 3(x-20)

*September 29, 2016*

**Chemistry**

after t days, the amount remaining will be 198.72 * (1/2)^(t/3.82) Now just plug in the number of days you need.

*September 29, 2016*

**Science**

depends on the size of the base, since pressure is in N/m^2

*September 29, 2016*

**Math**

"three more than one" means 1+3 = 4 any number between 10 and 20 has a tens digit of 1 put in a little thought on these. They are not hard.

*September 29, 2016*

**math**

2e^(-π/4 i) or 2e^(7π/4 i) since sinθ = y/r, and sin(-θ) = -sinθ, z* = x-iy = e^(-iθ)

*September 29, 2016*

**Math**

however 10^3 = 1000 your answer is 10^2

*September 29, 2016*

**science**

One reaction is Fe2O3 + 3CO = 2Fe + 3CO2 So, figure the number of moles of iron produced, and you will need 1/2 that many moles of Fe2O3. Then convert that back to mass

*September 29, 2016*

**math**

p/k = 80/12 = ?

*September 29, 2016*

**Algebra**

If the problem says that one angle of a triangle is three more than the other, then 36 + x + x+3 = 180 2x = 141 x = 70.5 You subtracted 39 on the left, but added 39 on the right.

*September 29, 2016*

**Algebra**

As you already heard: What don't you understand about the answer you already got?

*September 29, 2016*

**Math, Precalc**

sorry: 1st step is use cosB to get sinB.

*September 29, 2016*

**Math, Precalc**

you have cosB. Use that to get cosA. Now you cab find angle A using the law of sines: sinA/a = sinB/b Now, use the law of cosines to get side a: a^2 = b^2+c^2 - 2bc cosA

*September 29, 2016*

**percentage**

it's unfortunate that the 50K break points are included in the step function. Note that [x/50k] = 0 for x<50K, but 1 for x=50K So, assuming whole dollars, we have adjust our floor function to be [(x-1)/50000]+1 The first plan pays 3700 for 0 <= x <= 50000 3700 + ....

*September 29, 2016*

**math**

either convert all to decimal, or give them a common denominator Then it will be easy to tell

*September 28, 2016*

**Math**

(4y^5)^5 = 4^5 y^(5*5) = 1024y^25 because that is just 4y^5 * 4y^5 * 4y^5 * 4y^5 * 4y^5

*September 28, 2016*

**Pre-Calculus**

cot^2 = csc^2 - 1

*September 28, 2016*

**Math**

entire area - pool area - walkway area (8+2*.8)(5+2*.8) - 8*5 = ?

*September 28, 2016*

**Math**

no idea. what are you doing?

*September 28, 2016*

**Compound Interest**

Don't you have a formula for the future value of an annuity? If not, google can provide it -- or maybe your class textbook!

*September 28, 2016*

**Auburn Hugh School**

remember the 5-12-13 right triangle. Of course, there are many other non-integer solutions.

*September 28, 2016*

**math!! @bob**

a^2=b^2+c^2-2bc*cosA and we don't know A yet

*September 28, 2016*

**math!!**

sinB = 1/√10 b/sinB = c/sinC, so √3/(1/√10) = √10/sinC sinC = 1/√3 A = 180 - (B+C) sinA = (180 - (B+C)) = sin(B+C) = sinBcosC+cosBsinC = (1/√10)(√2/√3)+(3/√10)(1/√3) = (2+3√2)/(2√15) Now get a/sinA = b/...

*September 28, 2016*

**Algebra**

me, too

*September 28, 2016*

**Math**

(8-2)(4+6) = 60

*September 28, 2016*

**pre-calculus**

tan = sin/cos = 1/2

*September 28, 2016*

**pre-calculus**

sin(-x) = -sin(x)

*September 28, 2016*

**Pre-Calculus**

same bogus question. csc(theta) cannot be less than 1.

*September 28, 2016*

**geometry**

yes. As you could have verified by plugging in 2 to your function.

*September 28, 2016*

**Math**

(20)((-2 + 2) * 2^2 +6) = 120 what do you get for the other one?

*September 28, 2016*

**Math**

(3*5)+4-(14/2)=12

*September 28, 2016*

**Trig**

θ is in QIV, so x>0 and y<0 cosθ = x/r = 8/17 so, x = 8 y = -15 r = 17 Now recall the other trig functions: sinθ = y/r tanθ = y/x

*September 28, 2016*

**Algebra**

sure: y = -2x+3

*September 28, 2016*

**math**

substitute 7 for y division property (divide by 8)

*September 28, 2016*

**Math (calculus 3) - correction**

correct. good catch

*September 28, 2016*

**Math (calculus 3)**

recall that the height y = 1 + 40*sin(pi/6) t - 8t^2 (a) solve for t when y=1 (b) as with all parabolas, the vertex is at t = -b/2a

*September 28, 2016*

**Math**

This is called the power set.Any set of n elements has 2^n subsets. Just sum all the powers of 2 from 0 to n-1

*September 28, 2016*

**math plzz help**

330/(50+60)

*September 28, 2016*

**computer science**

Sorry about the formatting. I meant to say `Twas brillig, and the slithy toves Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe. "Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Beware the Jubjub bird, and...

*September 28, 2016*

**computer science**

`Twas brillig, and the slithy toves Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe. "Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Beware the Jubjub bird, and shun The frumious Bandersnatch!" He ...

*September 28, 2016*

**Geometry**

m<3 means the measure of angle 3 But, since we have no diagram, there's no way to tell anything about <1

*September 28, 2016*

**Calculus**

y = 4x + [5/sin x] = 4x + 5cscx y' = 4 - 5 cscx cotx y" = 5/2 csc^3(x) (cos(2x)+3) cos(2x)+3 is always positive. on (0,π) csc^3 > 0, so, y is concave up. similarly, y is concave down on (-π,0)

*September 28, 2016*

**physics**

since F = GMm/r^2 replacing r by 2r means the F is divided by 2^2

*September 28, 2016*

**science**

since g is inversely proportional to r^2, multiplying r by 2 means dividing g by 2^2

*September 28, 2016*

**math**

not sure what the special characters are. Copy/paste from word processor documents often mangle the fonts in a browser.

*September 28, 2016*

**Parabola**

2x^2-3x+4y+5=0 2x^2-3x+5 = -4y x^2 - 3/2 x + 5/2 = -2y x^2 - 3/2 x + (3/4)^2 = -2y + (3/4)^2 - 5/2 (x - 3/4)^2 = -2y - 31/16 (x - 3/4)^2 = -2(y + 31/32) So, the vertex is at (3/4, -31/32) You know that for the parabola x^2 = 4py here, 4p = -2, so p = -1/2 the focus is at a ...

*September 28, 2016*

**math**

the exterior angles of a decagon are all 360/10 = 36° So, 3x+6 = 36 x = 10 For the interior angles (each 144°), 3x+6 = 144 x = 46

*September 28, 2016*

**maths need help**

you will not solve this algebraically. Use a numeric approximation or read it from a graph, such as http://www.wolframalpha.com/input/?i=150sinx%3Dx%2B69.98

*September 28, 2016*

**algebra 1, solving polynomials**

there are no zeros. All you have is 8*12

*September 28, 2016*

**algebra**

1st step: multiply both sides by 17

*September 28, 2016*

**Urgent Math**

discs of thickness dx: v = ∫[0,1] πr^2 dx where r=y = 1-x^2 v = ∫[0,1] π(1-x^2)^2 dx shells of thickness dy: v = ∫[0,1] 2πrh dy where r=y and h=x=√(1-y) ∫[0,1] 2πy√(1-y) dy To integrate, use u^2 = 1-y dy = -2u du

*September 28, 2016*

**calculus help me**

y = cot(x+y) y' = -csc^2(x+y) (1+y') y' = -csc^2(x+y) - csc^2(x+y) y' y' (1+csc^2(x+y)) = -csc^2(x+y) y' = -csc^2(x+y)/(1+csc^2(x+y)) But, csc^2 = 1+cot^2, so y' = -(1+y^2)/(1+1+y^2) = -(1+y^2)/(2+y^2) or, you can say 1/y = tan(x+y) arctan(1/y) = x+...

*September 28, 2016*

**algebra**

good answer, but it does not address the question.

*September 28, 2016*

**math**

since distance = speed * time, 90(t-1) = 80(t+1)

*September 28, 2016*

**Maths**

sin^-1 (4x^4+x^2) = 1/6 pi 4x^4+x^2 = sin(pi/6) = 1/2 8x^4+2x^2-1 = 0 x^2 = [-2±√(4+32)]/16 = [-2±6]/16 = -1/2 or 1/4 x^2 = -1/2 x = ±i/√2 x^2 = 1/4 means x = ±1/2

*September 28, 2016*

**science**

F=ma, so 5 = 18M = 24m M = 5/18 kg m = 5/24 kg For both masses, 5 = (5/18 + 5/24)a a = 72/7 m/s^2

*September 28, 2016*

**Aptitude**

how many times around does each hand go? Each time around has circumference 2πr for the hand's radius.

*September 28, 2016*

**math trig**

see related questions below. Just use your numbers to follow the logic.

*September 28, 2016*

**Maths**

in English you don't lend from. You either borrow from or lend to fix that and all the other typos and try again.

*September 28, 2016*

**Calculus**

#1 You know that as x->0 sinx/x -> 1 tanx/x -> 1 You have θ/tan7θ = (1/7) (7θ/tan7θ) -> (1/7)(1) = 1/7 As the graph will show http://www.wolframalpha.com/input/?i=plot+y%3Dx%2F(tan7x),+-0.3+%3C%3D+x+%3C%3D+0.3 #2 some parentheses would help f(x...

*September 28, 2016*

**Math**

at r%, 8000(r/100) = 12000((r-1)/100) - 200

*September 28, 2016*

**Math**

8000(r/100) = 12000((r-1)/100) - 200

*September 28, 2016*

**Math**

A plug in t=0 B as with any parabola, the vertex is at t = -b/2a C see B D plug in t=2

*September 28, 2016*

**Math**

(a) and (b) look ok distance = speed * time, so since the time is the same (3.5 hrs), just add up all the speeds and multiply by 210 minutes: 210(8/80 + 6/42 + 15/75) = 93 miles

*September 27, 2016*

**calc**

#1: h(x) = k cos x 0 ≤ x ≤ 3π #2: h(x)= 10 − x 3π < x #2: limit as x->3π = 10-3π #1: h(3π) = k cos3π = -k So, you need -k = 10-3π k = 3π-10 #1: h(x) = (3π-10)cosx

*September 27, 2016*

**math**

what are path numbers?

*September 27, 2016*

**math**

slope: (-4-5)/(-2-1) = -9/-3 = 3 Now, using the point-slope form, y-5 = 3(x-1) at x=0, y=2 2*3+2 = 8 2(3+2) = 10 You took twice the sum of the slope and the intercept, but that was not the question.

*September 27, 2016*

**Calculus**

who needs a limit? f = x + 4/x f' = 1 - 4/x^2 So, f'(4) = 1 - 4/16 = 3/4 The tangent line at (4,5) is thus y-5 = 3/4 (x-4) using the limit f(4+h)-f(4) = (4+h)+4/(4+h) - (4 + 4/4) = ((4+h)^2+4)/(4+h) - 5 = ((4+h)^2+4-5(4+h))/(4+h) = (h^2+3h)/(4+h) = h(h+3)/(h+4) Now ...

*September 27, 2016*

**algebra**

well, it traveled 90 miles in 1 1/2 hours. So, it is still 1 1/2 hours away at 2:15

*September 27, 2016*

**mathematics**

see related questions below

*September 27, 2016*

**Math**

87 - 6 - x >= 32 81 - x >= 32 49 >= x so, at most $49 for shirts.

*September 27, 2016*

**math**

Plot the points. It will be clear that the line contains (0,-50). Or, now that you know the slope, use the point-slope form of the line with any of the points. How about (5,80) y-80 = 26(x-5) Now plug in x=0 and you will get y = -50.

*September 27, 2016*

**math**

no idea what you did wrong, since you didn't bother to show your work.

*September 27, 2016*

**math**

first, check to be sure there is a constant slope: (80+310)/(5+10) = 26 (262-80)/(12-5) = 26 (444-262)/(19-12) = 26 So, the slope is 26 For the y-intercept, since x=0 is 1/3 of the way from 5 to -10, the y-intercept is 1/3 of the way from 80 to -310: -50 26 + -50 = -24 Just to...

*September 27, 2016*