# Posts by Steve

Total # Posts: 49,574

**Math**

review the associative property of addition.

*March 21, 2017*

**College Algebra**

swap variables x = 4-y^2 y = ±?(4-x) But you need to pick the branch where 4-x >= 0. take a look at the graph and I'm sure you can answer the questions. http://www.wolframalpha.com/input/?i=%E2%88%9A(4-x)

*March 21, 2017*

**Calculus**

As always, draw a diagram. It is clear that if the length of the rope is z when the boat is x ft from the dock, z^2 = x^2+36 z dz/dt = x dx/dt Figure x when z=10, then just plug in your numbers and solve for dx/dt.

*March 21, 2017*

**Calculus**

I don't know how the liquid can drain and leave the substance behind, if it's dissolved. Maybe it's just in suspension, and the liquid drains through a filter. Anyway, the volume of water at time t hours is v = 60-4t The concentration is c(t) g/L = 100/v(t) = 100/(...

*March 21, 2017*

**Calculus**

y = 2?x - 4 since x and y are both functions of t, think chain rule: dy/dt = 1/?x dx/dt Now just plug in your numbers and you have dy/dt = 1/2 * 9

*March 21, 2017*

**Maths**

see your other posting -- this is just the same idea.

*March 21, 2017*

**Maths**

PQ is 4 units from AD and 6 units from AB. So, The slant height of ?ABP is ?(15^2-6^2) The slant height of ?ADP is ?(15^2-4^2) Now you can easily figure each area, and then the cost.

*March 21, 2017*

**Maths**

I have no idea which vertices are VEF, but just draw a diagram and note that the distance from the center pole to the base of the triangle is 1/2 the side length adjacent to the base of the triangular face. Then you can get the (slant) height of the triangle using the ...

*March 21, 2017*

**Math!**

see your other post in the related questions below.

*March 21, 2017*

**physics - eh?**

Try again, but not in gibberish

*March 21, 2017*

**angular velocity/ physics**

500 rotations is 1000? radians, so ? = 1000?rad/10s = 100? rad/s

*March 21, 2017*

**Calculus help**

Hmmm. Figured it out in two minutes! Less time than it took you to post the problem, I'd say...

*March 21, 2017*

**math**

b/(b+g) = 3/4 g = b-24 b/(2b-24) = 3/4 4b = 6b-72 b = 36 so, g=12 making 48 pupils in all

*March 21, 2017*

**grammar**

Extra credit: what's the difference between shall and will?

*March 21, 2017*

**Calculus (related rates)**

If the base of the ladder is x feet from the wall, and the ladder reaches up y feet, then we have x^2 + y^2 = 13^2 taking derivatives wrt t, x dx/dt + y dy/dt = 0 Now just plug in your numbers and solve for dy/dt (note that at the moment in question, you conveniently have a 5-...

*March 21, 2017*

**Calculus (related rates)**

do this like your earlier one, using the chain rule.

*March 21, 2017*

**Calculus (related rates)**

just use the chain rule. Since x and y are both functions of t, dy/dt = (4x+2) dx/dt Now just plug in your numbers

*March 21, 2017*

**Calculus**

just crank it out. The acceleration is a(t) = 0.0044875t^2 - 0.17879t + 18.86 a(t) has a max/min when da/dt = 0 da/dt = 0.008975t - 0.17879 da/dt=0 at a=19.9209 a(10.9209) = 17.0792 Since a(t) is a parabola, there is no maximum value, but in the domain [0,50.2], the maximum ...

*March 21, 2017*

**Math**

Draw a diagram. If the ladder's length is z, and the base of the ladder is x feet from the fence, then by similar triangles, you can see that z/(x+3) = ?(x^2+9)/x z = (x+3)?(x^2+9)/x dz/dx = (x^3-27) / (x^2 ?(x^2+9)) dz/dx=0 when x=3 z(3) = 6?18/3 = 6?2

*March 21, 2017*

**Math Check!**

2975*1.04^2.5 = 3281.48 But, technically, since the interest is not compounded till the end of the year, you might get 2975*1.04^2 = 3217.76 Since that is not listed, I'd go with B So, how did you get D? That's over double the initial amount. Not likely!

*March 21, 2017*

**Algebra**

.03b + .10(20000-b) = .08*20000

*March 21, 2017*

**maths**

a = 4b .17a + .10b = 234 so, .78b = 234 b = 300

*March 21, 2017*

**Math (higher level) 2nd year**

(3x-2)(2x-4) = 14 6x^2-16x-6 = 0 2(x-3)(2x+1) = 0 x = 3 So the bed is 7x2 But you could have guessed that at first, since 2 and 7 are the only factors of 14...

*March 21, 2017*

**real estate**

x * 1.06^2 = 140000

*March 21, 2017*

**science**

see related questions below.

*March 21, 2017*

**Relative Clauses and Pronouns**

all look ok to me. Of course, the purists would write 5. This is the tiger for which the hunters have been looking. Like the small boy who noticed his father had brought the wrong bedtime story, and said: What did you bring that book I don't want to be read to out of up for?

*March 21, 2017*

**Calculus**

think of the volume as a stack of discs of thickness dx, and you have v = ?[0,?] ?r^2 dx where r=y=cos(cos(x)) v = ?[0,?] ?cos^2(cosx) dx This is not an elementary integral, so some numeric method is needed. However, using some symmetry, v = 2?[0,?/2] ?cos^2(cosx) dx and you ...

*March 21, 2017*

**Calculus**

Each semicircle resting on the x-y plane has radius x=?(16-y^2). Adding up all the slices, and using symmetry, we have v = 2?[0,4] 1/2 ?r^2 dy = ??[0,4] (16-y^2) dy = 128?/3 bobpursley's solution is much more intuitive and geometric, though, eh?

*March 21, 2017*

**Calculus**

Hmmm. Let me take a stab at it. AT (-4,1) we have ln(x^2-15y) = ln(1) = 0 Hmmph. Can't make out a reasonable interpretation that is zero on the right. Anyway, regardless, let's just say that it is ok as it is. Then we have, taking derivatives of both sides, using the ...

*March 21, 2017*

**Math**

correct

*March 21, 2017*

**math**

Since the axis of symmetry is x=3 and the y-intercept is E, the parabola is f(x) = a(x-3)^2 + E since E is the y-intercept of the parabola, E = -7/2 f(x) = a(x-3)^2 - 7/2 Now you know that (7,0) is on the parabola, so a(7-3)^2 - 7/2 = 0 16a = 7/2 a = 7/32 f(x) = 7/32 (x-3)^2...

*March 21, 2017*

**math**

well, ?5 ? 2.236 I assume you can mark that on the number line. . .

*March 21, 2017*

**math**

{1,2}?{2,3} = {1,2}?{2,5} I'm sure you can handle the Union one...

*March 21, 2017*

**math**

I believe exterior angles are 180 - interior angles. Their sum is 360.

*March 21, 2017*

**Algebra**

.06^(1/12) = ?

*March 20, 2017*

**algebra**

L(L-3) = 46.75 solve for L and W, then P = 2(L+W)

*March 20, 2017*

**Science**

you'll probably get a faster response from google: https://www.google.com/search?q=What+are+the+uses+of+reactivity+series&ie=utf-8&oe=utf-8

*March 20, 2017*

**MAATH!!**

correct

*March 20, 2017*

**Math**

720 = 36*20 so, count the good ones here and multiply by 20 to estimate the larger amount.

*March 20, 2017*

**Science**

KE = 1/2 mv^2 and that's "wrecking" ball, but it does wreak havoc ...

*March 20, 2017*

**maths**

Now, use the fact that v(0) = 10 (4t^5/5)-(8t^3/3)-9t+v0 = 10 at t=0 So, v0 = 10, and thus v(t) = (4t^5/5)-(8t^3/3)-9t+10 Now go on to x(t), using x(0) to find the constant of integration.

*March 20, 2017*

**Physics**

Adding 20cm^3 of liquid added 20g of mass, so the density is 20g/20cm^3 = 1 g/cm^3

*March 20, 2017*

**calculus**

y" = 4 y' = 4x+c y'(1)=10, so 4+c = 10 c=6 y' = 4x+6 No do the same to move on to y.

*March 20, 2017*

**Maths**

4/5 the time, so 5/4 the workers: 80 so, another 16 are needed.

*March 20, 2017*

**ALGEBRA I**

1st step: write a function for each company. For example, Rider: y = 50 + 0.50x now what?

*March 20, 2017*

**Algebra II**

assuming a linear rate of depreciation, the car loses $3900/year. So, after x years, its value is v(x) = 16800 - 3900x

*March 20, 2017*

**Math**

Assuming you meant f(x)=-2x*4^(x-1)+3 the domain of all polynomials (-2x) is (-?,?) the domain of all exponentials is (-?,?) so, the domain of f(x) is likewise (-?,?) now work with the ranges in like wise. x -> (x-h) translates right by h y -> (y-k) translates up by k y...

*March 20, 2017*

**Algebra**

compare Bh to 1/3 Bh in each case for volume similarly for area

*March 20, 2017*

**Math**

just plug your points into x^2/a^2 + y^2/b^2 = 1 then solve for 1/a^2 and 1/b^2

*March 20, 2017*

**Math**

The direction numbers for the last two points make the line from t=0..1 x = 2-t y = 0-t z = -1+4t So, backing up to z=3, -1+4t = -3 t = -1/2 a = x(-1/2) = 5/2 b = y(-1/2) = 1/2

*March 20, 2017*

**Calculus - Integrating**

The problem is that you did not have du in your integrals. You lacked the extra 2x dx in your integrands. u = x^2+1 du = 2x dx x = ?(u-1) So you have ?x/?(x^2+1) x dx = 1/2 ??(u-1)/u du which isn't really much better Try using a trig substitution: x = tan? x^2+1 = tan^2...

*March 20, 2017*

**math**

s = t^3-9t^2+3t+1 v = 3t^2-18t+3 = 3(t^2-6t+1) so, solve for t when v=-24 a = 6t-18 then plug in that t to find v and a. what is your problem with minus signs (-) ? over- and under-score really are ugly! x^2 cosy - siny = 0 Surely you can plug in the point to verify it fits! ...

*March 20, 2017*

**MATHEMATICS**

plug your numbers into the formulas found here: https://www.google.com/search?q=cone+area&ie=utf-8&oe=utf-8

*March 20, 2017*

**Science**

2Mg + O2 -> 2MgO now convert to moles for amounts needed

*March 20, 2017*

**College algebra**

If the half-life is k years, then after t years, (1/2)^(t/k) remains. Thus, to find k, solve (1/2)^(400/k) = 0.7 600 = 3/2 * 400, or 1.5 half-lives. So, the amount remaining after 600 megayears is (1/2)^(3/2 * 400/k) = (1/2)^(400/k)^(3/2) = 0.7^(3/2) = ?

*March 20, 2017*

**English**

the literary device of foreshadowing is used in which of the following excerpts? They're spoiled and we're spoiled Those screams -- they sound familiar I have a feeling it'll be Africa again before then They're not old enough to do that alone, I explained My ...

*March 20, 2017*

**English**

thank you

*March 20, 2017*

**English**

my second choice was number 2

*March 20, 2017*

**English**

Which of the following is a way that imagery can be used? to present facts during debates to inspire audiences during speeches to entertain readers with a play on words to impress readers with facts and evidence My answer is the third one

*March 20, 2017*

**English**

Then it would have to be subjective

*March 19, 2017*

**English**

when doing research writing it is important to avoid being? timely, detailed, objectives, subjective My answer is detailed

*March 19, 2017*

**Mathematics for social science**

20P3 10C4

*March 19, 2017*

**English**

I agree with your comments. thank you

*March 19, 2017*

**English**

Absurdism is the attempt to show the ________ of the human condition. silliness seriousness uniqueness hopelessness my answer is the last one

*March 19, 2017*

**English**

thank you

*March 19, 2017*

**English**

Scientists report (1) that creatures living in the deep sea are in danger of starving to death. The underlined part of sentence 1 is what kind of clause? adverbial clause adjectival clause noun clause Independent clause My answer is independent because if you remove the word ...

*March 19, 2017*

**math**

75% = 3/4 He gave 42 to Joe

*March 19, 2017*

**math**

I'm assuming your asking how many did Keith get? 56*3/4=42 Leon gave to Joe 42*2/7=12 Joe gave to Keith 3/4= 75% 2/7=28.6%

*March 19, 2017*

**Calculus**

The weight of oil in the tank is w = (20*25? m^3) * (820 kg/m^3) * 9.8 = 4018000?N The center of gravity of the oil is 20m from the top of the tank, so the work required to empty the oil is 4018000? * 20 = 80360000? J Or, using calculus, the weight of oil in a thin layer of ...

*March 19, 2017*

**Physics**

Scroll down some here, and all is explained. http://www.insula.com.au/physics/1279/L14.html

*March 19, 2017*

**Math Functions Functions**

to shift right by h, replace x with (x-h) to shift up by k, replace y with (y-k) Thus, y-3 = (x-2)^2 shifts y=x^2 right 2 and up 3. Reflecting across an axis changes the sign of the other variable. Thus -y=x^2 reflects y=x^2 across the x-axis. Now see what you can do.

*March 19, 2017*

**math- factoring**

If two polynomials are identical, all the coefficients must match. So, a = 2 b = -13 c = 21

*March 19, 2017*

**Math**

(5?3,5)+(0,-4) = (5?3,1)

*March 19, 2017*

**Math**

in standard form, you have x^2+4x - 4(y^2-6y) = 28 x^2+4x+4 - 4(y^2-6y+9) = 28+4-4*9 (x+2)^2 - 4(y-3)^2 = -4 (y-3)^2 - (x+2)^2/4 = 1 Now use that with your standard properties of hyperbolas. check with this: http://www.wolframalpha.com/input/?i=hyperbola+(y-3)%5E2+-+(x%2B2)%...

*March 19, 2017*

**Math**

|p| = ?(42^2+35^2) = 7?(6^2+5^2) tan? = 35/42 = 5/6

*March 19, 2017*

**Math**

.075x + .12(5000-x) = 819

*March 19, 2017*

**Physics**

(10cos37,-10sin37)+(-14,0) = (-6,-6)

*March 19, 2017*

**Advanced Functions**

look at the differences. 1st: -0.2, -0.6, -1.0, -1.2, ... 2nd: -0.4, -0.4, -0.4, ... so, look for a linear relationship between y and x^2: y = 3-5x^2 fits pretty well, at least at first

*March 19, 2017*

**Math**

cos(2x) = 1 - 2sin^2(x) now just use your numbers.

*March 19, 2017*

**Math**

A. 32.65+(38.4-25) = ? B. 32.65+(x-25) = 50.15

*March 19, 2017*

**numerical methods in finance**

Just plug in your formula. If you have trouble with that, youtube has several videos showing examples.

*March 19, 2017*

**math**

small = 47/22 - 1/2 large = small + 40/11 small = 36/22 large = 116/22

*March 19, 2017*

**Geometry**

it is easy to show that ?NOD ? ?MOB check out vertical angles and recall that the diagonals bisect each other.

*March 19, 2017*

**Math**

y = 550 * 0.948^t

*March 19, 2017*

**Math**

recall that the sum of two adjacent angles is 180, so ...

*March 19, 2017*

**Math 120**

(3990-1890)/3990

*March 19, 2017*

**Maths**

clearly, P(3k) Q(2k)

*March 19, 2017*

**Math**

review the cot(x) function: h cot30 - h cot45 = 1

*March 19, 2017*

**Math**

tan? = 9/3 and try proofreading what you type. It's a mess.

*March 19, 2017*

**calculus**

what, you can't just plug in the 6 values of t? Even after the explicit example given? No calculus needed here, just basic algebra!

*March 19, 2017*

**Maths**

gotta be (d) since the point spread does not change

*March 19, 2017*

**Math**

o = 3s o+3 = 2+2(s+3) Olivia is 15

*March 19, 2017*

**Math**

construct a 60° angle AOB Bisect it. Measure out the hypotenuse and mark A. Construct the perpendicular to OB.

*March 19, 2017*

**College Algebra**

P(t) = 15.1*2.06^t

*March 19, 2017*

**Algebra**

This is just an extension of finding the line passing through two points. Plug in the points for Ax+By+Cz = 0 and solve for A,B,C.

*March 19, 2017*

**Physics**

F = ma constant velocity means a=0

*March 18, 2017*

**Calculus**

Huh, you can't figure the dimensions of s square of area A? The maximum area for a given perimeter is a square. The minimum perimeter for a given rectangular area is a square. So, the length and width would both be ?A But, since you seem to be taking calculus, look at the ...

*March 18, 2017*

**Calculus**

a square

*March 18, 2017*

**algebra**

hint: 24 = 5*5 - 1

*March 18, 2017*

**Linear algebra**

Clearly you did not continue reading to the section where it showed how to find Q1 and Q2.

*March 18, 2017*