# Posts by STEVE

Total # Posts: 50,543

**physical science**

work = PE = mgh

**Math**

$80

**math**

Cool. Now where the heck is PR? Get with it, ok?

**help**

force is N = kg-m/s^2 work is J or N-m

**Math**

I hope you are not the one who has already posted this several times, receiving an answer each time. It is (11+9)/2 * 6 * 16/12

**algebra**

multiplying by 10, we have -2x+25 = 22 ...

**Math**

17000*1.03^5

**algebra 2**

x = (6+y)/(2y) 2xy = 6+y y = 6/(2x-1)

**math**

Note that ?MQP = ?MPQ so ?QMP is isosceles. MQ = MP = 18 ?MRQ is 30-60-90, with a hypotenuse of 18 RQ = 9?3

**math**

and PR is where?

**math**

where is M?

**Math**

well, the area is (11+9)/2 * 6 = 60 m^2 How many boxes is that? So, how much cost?

**Math**

you cannot simplify the log of a sum. Since there are no common factors to remove, this is as simple as it gets. Unless you mean log 6(7m+3q) = log 6 + log (7m+3q)

**Math**

Since 100 = 10^2 take the square root of both sides, and you have 10 = 100^(1/2) x = 1/2

**science**

PE is measured in J or N-m PE = mgh

**algebra**

V=kT/P so PV/T = k, a constant. You want T such that 10*74/T = 8*42/84 also, "cm to the 3" is written cm^3

**algebra**

3x+10 >= 4 3x >= -6 ...

**Algebra 2**

(x+2)(x-3) --------------- (x+2) This is equal to (x-3) for every value of x except -2, where it is undefined.

**Math**

recall that (a+b)^2 = a^2+2ab+b^2 so, take 1/2 of the middle coefficient and square it.

**Math**

since the center is at y=5, and it is tangent to the x-axis, the radius is 5. Now, what is the standard equation for a circle?

**Math**

well v increased by 3 m/s in 8 seconds. now, what is the definition of acceleration?

**Math**

figure the lengths of the sides. Then use the law of cosines. c^2 = a^2 + b^2 - 2ab cosC

**Math**

x^2?6x+9+y^2+2y+1 = 25 (x-3)^2 + (y+1)^2 = 5^2 Look familiar?

**math**

Draw a diagram, where a radius bisects the chord. You will see that the arc is subtended by the angle ?, where sin(?/2) = 9/14 The arc length is then s = r?

**Rox**

yes

**math**

top is 14 left is 12 right is 10 bottom is 20 If the figure is a trapezoid, then 144-x^2 = 100-(6-x)^2 x = 20/3 The height h is h^2 = 144-(20/3)^2 h = 8/3 ?14 So, the area is a = (14+20)/2 * 8/3 ?14 = 136/3 ?14

**Maths**

what is the shape of the rope? straight lines? parabola? catenary?

**Science**

1 and 2 are ok. On #3 you confuse frequency and wavelength. (and that's "greater")

**Physics**

conserve momentum: 5v = (8000+5)*0.50

**Maths**

(15 km/hr * 10^5 cm/km) * (49? cm^2) * x hr = (50m * 44m)(100cm/m)^2 * 21cm x = 2 hr

**algebra**

you don't say whether the values given are opposite or adjacent angles. So, you have one of two cases: x+40 = 3x-20 x+40 + 3x-20 = 180 Pick the one you want, solve for x, and then you can answer the questions.

**math**

pair them up 2,2n 4,2n-2 6,2n-4 ... What is the average of each pair? Or, consider their sum: 2+4+...+2n = 2(1+2+...+n) = 2*n(n+1)/2 = n(n+1) So, what is the average of that sum?

**math**

(a + b+10)/2 = (a+b)/2 + 5

**maths**

N arctan(8/5)° E

**mathematics**

remember the point-slope form of a line. The line with gradient m through (h,k) is y-k = m(x-h) Now just plug in your numbers.

**calculus**

y = -(x-3)(x-4) So, using discs of thickness dx, v = ?[3,4] ?r^2 dx where r=y v = ?[3,4] ?(x^2-7x+12)^2 dx = ?/30 Using shells of thickness dy, and taking advantage of the symmetry, v = 2?[0,1/4] 2?rh dy where r=y and h=?(1/4 - y) v = 2?[0,1/4] 2?y?(1/4 - y) dy = ?/30

**Math**

well, there are 10 choices for each digit, so ...

**math**

first step: what is the probability of rolling a 7?

**Math**

x^2-x-6 = (x-3)(x+2) x^2-5x+6 = (x-3)(x-2)

**calculus**

each shell has thickness dx, so v = ?[1,3] 2?rh dx where r=x-1 and h=y-3 v = ?[1,3] 2?(x-1)(4x-x^2-3) dx = 8?/3 as a check, using discs of thickness dy, v = ?[3,4] ?(R^2-r^2) dy where R=(2+?(4-y)-1) and r=(2-?(4-y)-1) v = ?[3,4] ?((1+?(4-y))^2-(1-?(4-y))^2) dy = 8?/3

**calculus**

Each shell has thickness dx, so v = ?[0,2] 2?rh dx where r = 9-x and h = 8-y v = ?[0,2] 2?(9-x)(8-x^3) dx = 984?/5 as a check, using discs (washers) of thickness dy, v = ?[0,8] ?(R^2-r^2) dy where R=9 and r = 9-x v = ?[0,8] ?(9^2-(9-?y)^2) dy = 984?/5

**Math**

x/4 + 2 = -2 x/4 = -4 x = -16

**General Math**

Presumably, the same percentage of seals was tagged as was found in the later sample. So, 6982/x = 245/700

**8th grade math asp help**

as you can see, no pictures here.

**Crimal Justice**

thank you

**Crimal Justice**

Julia has served one year of her 10-year sentence in prison. She has behaved herself, work at the library, and has not acted out in any way. She is hoping that at her next hearing judge will reduce her sentence. What type of sentence is julia hoping that at her next hearing ...

**Math**

well, a common right triangle is 5-12-13

**calculus**

because y is a function of x. You must use the chain rule. d/dx (3y^2) = d/dy (3y^2) * dy/dx

**calculus**

ln(x+y+3) = xy + y^3 (1+y')/(y+x+3) = y + xy' + 3y^2 y' Collect terms and solve for y': y' = 1-y(x+y+3) -------------------------- (x+y+3)(x+3y^2)-1 so, at (-4,2), y' = -1/7 So, now you have a point and a slope, and the ...

**maths extrema need hlp**

for extrema, you need ?f/?x and ?f/?y = 0 ?f/?x = cosx + cos(x+y) = 0 ?f/?y = cosy + cos(x+y) = 0 recall that cos ?/3 = -cos(2?/3) So that should get you started.

**mathematics plz need help sir steve**

Do you mean the Jacobian? F1x = 4x^3y^3 F1y = 3x^4y^2 F2x = 35x^6 F2y = 3cos(3y) So, the determinant of J(f1,f2,x,y) is (4x^3y^3)(3cos(3y))-(35x^6)(3x^4y^2) = 12x^3y^3 cos(3y) - 105x^10y^2 See http://www.wolframalpha.com/input/?i=jacobian+of+(x%5E4y%5E3,+5x%5E7%2Bsin(3y))

**Math**

All except #11 rely on figures not available here. As for #11, the words "right," "acute" and "obtuse" refer to angles, so you know that A,C,D are all wrong.

**Algebra**

You know the factors will be among (2x+?)(x-?) (2x-?)(x+?) where the ? can be 2,3 or 1,6 Now you just have to play around till you find what works. That 13 in the middle is a good indicator that 1,6 will be involved, since it is so big. Now recall that 13 =12+1, so I expect ...

**math**

88/9 = 9 7/9

**math**

Draw a diagram. Label it T = top of pole B = bottom of pole S = tip of shadow In ?SBT, ?S = 8° ?B = 102° So, ?T = 70° Now, using the law of sines, the pole's height, BT can be found using BT/sin8° = 16/sin70° This assumes that the angle of elevation is ...

**math**

have you tried the law of cosines?

**Algebra**

Your text above seems to indicate that the last problem was to find the domain of ?(6x-18) You know that square roots of negative numbers are not real, so the radicand must be positive That is, the domain of ?x is x >= 0 So, the domain of ?(6x-18) is 6x-18 >= 0 x >= 3...

**Algebra**

By this time, you should have been able to find your answers in what was written in the responses.

**@Typos ? Us**

As you can see from the responses here, if you want a good answer, you need to be clear on just what it is you are asking. It is not our job to figure out what you mean -- it is your job to say it so clearly that you cannot be misunderstood!

**Algebra 1**

Of course, if you knew how to solve them, you would naturally know how to show your work ... #1 As always, (a+b)^2 = a^2+2ab+b^2 (3?6 + 5?10)^2 = (3?6)^2 + 2(3?6)(5?10) + (5?10)^2 = 54 + 30?60 + 250 = 304 + 60?15 So, (3?6 + 5?10)^2 - 286 + 60?15 = 304+60?15 - 286 + 60?15 = 18...

**MATH**

writing the ratios as fractions, you have a/b = c/d and c/d = e/f So, transitivity means that a/b = c/d = e/f a/b = e/f

**Spanish**

I hope a Spanish speaker can help you on this. My Spanish is rudimentary, but even I can tell that there are some serious grammatical errors in this essay.

**Maths**

oops. I misread. the problem. The above rates are for 1/2 yearly accrual of interest. For annual compounding, the amount is 70000(1+.10)^(3/2) = 80758.28 Actually, though, after a year and a half, the annual rate has only been applied once, so the amount in the account is only...

**Maths**

compound: 70000(1+.10/2)^3 = 81033.75 simple: 70000(1+(.10/2)*3) = 80500

**math**

20 - 2(-4)^2

**Math**

b+g = 1420 3g/4 = b/2 . . .

**maths**

6:40 = 9:60

**Geometry**

if EFGH is a square, then there are 4 equal sides. Can you do it now?

**Math**

clearly, 14 * 1/17

**science**

Since pressure is N/m^2, the whole elephant would exert (500*10 N)/(4*0.08m^2)

**math**

These are the 6 ways to pair up the vowels: AA EE AE AE AE EA EA EA EA AE EE AA Now consider the ways if you use each pair as a single letter. But consider duplicates.

**math**

It crosses the x-axis whenever sinx = -1/2. That is, whenever x = (2k-1)? + ?/6 x = 2k? - ?/6 for any integer k. If you just wanted the graph, why not visit any of hundreds of graphing sites, such as this one: http://www.wolframalpha.com/input/?i=1%2B2sinx

**Math**

distance = speed * time, so (3 1/2)*(1 1/3) = 7/2 * 4/3 = 14/3 = 4 2/3 miles

**Algebra2**

divide by 64 to get x^2/4 - y^2/16 = 1 Review your material on hyperbolas, and see whether you can see how to get the information shown here: http://www.wolframalpha.com/input/?i=hyperbola+x%5E2%2F4+-+y%5E2%2F16+%3D+1

**Algebra2**

What are the vertices, foci, and asymptotes of the hyperbola with the equation 16x^2-4y^2=64? What would the formulas be to find the answers?

**Advanced Functions - oops**

sorry. You did yours in minutes. He did his in seconds, but the ratio is the same.

**Advanced Functions**

You have figured the period in hours. Reiny did it in minutes, so his period is 6pi/60 = pi/10

**Advanced Functions**

see related questions below. If you're still stuck, show us your work and your sticking point.

**Math**

18" = 1.5 ft So, the area of the box is 2(3.5*1.5 + 3.5*2 + 1.5*2) = 30.5 ft^2 Or, using the Ph+2B, we have 2(3.5+1.5)*2 + 2(3.5*1.5) = 30.5 ft^2 Now add the 2.5 to get 33 ft^2 The first formula uses the fact that you have two sets of rectangular faces. The area of each ...

**Math**

what, you can't plug in t=15?

**Maths**

The area could also be considered using horizontal strips. In that case, each strip lies between the line and the curve, with no break in the boundary. Then the area is ?[0,27] (y/27 + 2)-?y dy = 27/4

**Maths**

You cannot just integrate on [0,2] to get the area. That ignores the part between the curve and the line on the interval [2,3]. That is ?[2,3] x^3-(27x-54) dx = 11/4 Add that to your area of 4, and you get 27/4

**geometry**

Where are P and Q in relation to K and N?

**Mathematics**

To start with, Construct a right angle. Bisect it. Measure off the lengths. Label the points. Then figure out what the heck angle "DE" is.

**math**

Suppressing all those trailing zeros, 25b + 10c <= 250 25b >= 50+10c b >= 5 c >= 7

**Math**

Draw a diagram. It should be clear that if B is h meters tall, (40-h)/10 = tan 26°

**math**

it is in simplest form if the numerator and denominator have no common factors.

**Chemistry**

Determine the Enthalpy of combustion of ethyne (C2H2) using the following enthalpies of formation; Data: DHf°(H2O)= -285.9kj/mol DHf°(2H2)= +226.7Kj/mol DHf°(CO2)= -393.5Kj/mol Equation; C2H2--------->CO2 + H2O

**calculus**

See here: http://www.intmath.com/applications-integration/5-centroid-area.php scroll down for a nice example, with steps for solution.

**calculus**

the volume of water is 10^2 * ? * 2.5 = 785.4 m^3 That much water weighs 785.4 * 1000 * 9.8 = 7696920 N The center of mass is 1.75m below the top of the pool, so the work required to lift it all is 7696920N * 1.75m = 13,470,000 J But, if you want to use calculus, consider a ...

**physics**

why do you say it is abnormal?

**physics**

(70.71i+70.71j)-(0i+100j) = 70.71i-29.29j

**calculus**

see related problems below.

**Advanced Functions**

cos(pi/2 - x) = sin(x) so, cos(?/2 - ?/10(t-5)) = sin(?/10(t-5)) you should probably simplify that.

**Math**

-4 < x < 5 -16 < 4x < 20 -11 < 4x+5 < 25 so, ...

**Math (Stats)**

I agree

**Math (Stats)**

So, what does the correlation coefficient tell you about the accuracy of the regression line?

**geometry**

what, you can't plug in values? A(1) = -2+(1-1)(-2.2) = -2 A(2) = -2+(2-1)(-2.2) and so on hint. Just keep subtracting 2.2 to get the next term.

**Maths**

To be divisible by 4, the last two digits must be a multiple of 4. Using those digits, the only possibilities are 12,16,28,56,88 There are 5^5 possible 5-digit numbers. Of those, 5^3 * 5 = 5^4 end in those digits. So, 5^4/5^5 = 1/5 of the numbers will be divisible by 4. Adjust...

**algebra**

z = kyx^2 so, z/(yx^2) = k is constant. So, you want x such that -96/(2x^2) = -84/(7*4)