# Posts by STEVE

Total # Posts: 52,076

**Physics**

first, how long till they meet? Check to see when the heights are the same: 25t-5t^2 = 25-5t^2 Now use that value of t to get the height.

**Math**

2/5 + 1/3 = 6/15 + 5/15 = 11/15 that's how much she spent. So how much was left?

**math**

come on, guy -- do the math (65/12 + 12/7) -------------------- = ? (65/12 - 12/7)

**English**

Q1: no difference. The "with me" is implied -- how could you take him home with someone else? Q2: #1 and #2 are basically the same: close proximity at the time. #3 is a little more general, since they may not actually be physically nearby at all times.

**math**

(3/8 - 5/12) / 1/(-15/8 * 16/27) = (9/24 - 10/24) * (-15/8 * 16/27) = (-1/24) * (-10/9) = 5/108

**Math, science.**

consider the fact the two angles add to 180° so, what is the sum of their bisectors?

**sjps science**

sentence is gibberish no choices listed

**Math**

5588 6299 and others

**algebra**

cosA/(1-sinA) * (1+sinA)/(1+sinA) = cosA(1+sinA)/(1-sin^2A) = cosA(1+sinA)/cos^2A = (1+sinA)/cosA = secA + tanA You can easily see that your original equation is false. Just use A = pi/4

**Math**

C(x) = 40x

**AOOOGAH!! Homework Dump!!**

not here, buddy...

**physics**

by "length" do you mean the tread width? Otherwise, what difference does it make how long the step is? Anyway, just figure the distance to cover one step (up and across), and multiply by 5. then use the Pythagorean Theorem on the total horizontal and vertical ...

**Math**

think linear inertia resisting the centripetal force

**plane geometry**

well, r = s/?3

**maths**

Hmmm. I'd say that AC=8 Also, the 3rd side is either 8 or 12, right?

**maths**

what, no calculator? just enter the expression into google. Be sure to use enough parentheses. If you enter your text at wolframalpha.com, it will show you how it interpreted your input.

**physics**

v(t) = 20-10t Think on it. Each second, the velocity decreases by 10 m/s

**geometry - incomplete**

without a diagram, it is impossible to tell how the angles are related.

**math**

just write it as math, and then solve. If the AP has 1st term a, and the GP has first term g, then a+2d = g a+3d = gr a+7d = gr^2 10/2 (2a+d) = 85

**circles**

they are exactly the same equation.

**Math**

(1/2)^(10000/24000) = 0.74915 (1/2)^(30/n) = 4^(-1/3) n = 45

**trigonometry**

I did this one already, but your typo made it work out wrong. You have fixed the typo, so just change the 15 to 5, and work it out. What do you get?

**Math**

all three of these are basically the same. You have a constant value up to some value, then a linear function after that.

**math urgent help**

that's better.

**math urgent help**

almost. You forgot the 2x^2 f(-4) = 2*16+20-3

**Math**

2nd piece: f(d) = 8.00 + 1.50?d-4? for d>4 Now you should be able to provide the other piece.

**plane geometry**

I see you could not be bothered to study the url I gave you earlier. I'll do most of your work for you. the area of the triangle, found using the method of your choice, is 2310 so, the radius of the excircle is (68+75+77)/2 - 68 = 2310/42 = 55 thus, the circle's area ...

**Math**

this is an old and intractable problem. Read about the Traveling Salesman problem.

**maths**

try using the minus sign (-) instead of the underscore (_) for subtraction. 2x^2-3x-5=0 (x+1)(2x-5) = 0 ...

**Math**

72 = 8*9 64 = 8*8

**Math**

which one is a multiple of 9? go with that one.

**maths**

5008

**Physics**

The plane takes a heading, not a bearing. So, draw the velocity triangle. You should be able to see that speed: s = ?(250^2+50^2) heading: tan? = 50/250

**maths**

correct

**Physics**

30 minutes is 1/2 hour, so 70 km/hr * 1/2 hr = 70/2 = 35 km

**Math**

come on, give it a little thought. What is the largest digit? 9 so, now you have 9xxxxx work on the other sentences. they are all very easy.

**Math**

42

**Physics**

ever hear of google?

**physics**

as with all geometric objects, the volume grows as the cube of the linear scale factor. I assume your coefficient is 12*10^-6 cm/°K (can't quite tell from your notation). Anyway, if the linear size grows by 1.0002, then the area grows by 1.0002^2 and the volume grows ...

**math**

subtract the pool from the total to get the area of the walk: (15+2w)(10+2w) - 15*10 = 116 now just solve for w

**Mathematics**

t(m) = 300 for m <= 100 t(m) = 300+(m-100) for m > 100

**science**

since PV = kT (2P)(2V) = 4PV = k(4T) so, 4 times the (Kelvin) temperature

**physics**

F = ma, so a = F/m a1 = 72/m1 a2 = 72/(m1+m2) not sure whether the "same force" means the same 72N force, or another force of equal size. If the latter, then both forces acting together would impart an acceleration of (72+72)/(m1+m2)

**Algebra**

they are the same line, so ...

**Clinical Calculations**

well, 117/9 = 13, so that's 13 "doses" 500 mg/8hr = 1500mg/day Hmmm. we said he'd need 13 times the base amount

**Math**

just check the possibilities. You want two evens + an odd to add up to 11. 227 443

**Math**

try again, after fixing your typo.

**trigonometry**

this url shows how to figure the radius of an escribed circle. https://math.stackexchange.com/questions/1674656/radius-of-an-e-circle-in-terms-of-triangles-sides-and-area

**trigonometry**

you are just interested in the east-west distances traveled. When they are the same, B is north of A. So, t hours after A set off, you want (15 sin42.58°)t = (7 sin46.33°)(t-2) This has a solution of t = -2 huh? I suspect a typo. A is going twice as fast, for two hours...

**trigonometry**

If we call h = height of flagpole t = height of tower The four angles are x,y,a,b in the order named, then we have h/120 = tanx t/120 = tany x = 2y a+b = pi/2 that means that sin(a+b) = 1 That's a lot of equations to work with, but we know that tanx = tan 2y = 2tany/(1-tan...

**trigonometry**

bisect the base, and you can see that the two equal sides have length 6/sin40° proceed from there.

**Maths**

The interest earned each year is r/100 * 3500. So, after 3 years, the interest amounts to the amount of increase: 3500*3r/100 = 6020-3500

**maths**

pretty big box!

**maths**

the wood is the difference between the outer and inner volumes. In cm^3, that is 200*20*22.5 - (200-5)(20-5)(22.5-2.5)

**math**

not sure what all the extra punctuation means. But rounding off to thousands means ....(x-1)501 - ....x499 round to ....x000

**Math**

only 186 is a multiple of 6. So, $2.85 * 186/6 = ?

**Math**

940 = 2^2 * 5 * 47 So the only choices are 2,5,10

**lmatha**

6300*1.07*(8/3)

**math/statistics**

If you made a Venn diagram, and remember how they work, then (a) (120+146+68)-(36+27+23)+x = 400-132 (b) now use the Venn diagram to add up the three parts that don't intersect any others.

**math**

sounds right, if you want your angle in degrees.

**sir steve reiny bob damon need help maths**

sure is hard to interpret your prose. If x is the input, then it appears that you are saying (16/25) * 1/(4x^2)*(1+12x/5) = 1 somewhere there should be a subtraction, since you use the word "difference" but I can't figure out what, unless maybe there's a (12/...

**College - Unweighted GPA**

total GPA It does not say anything about senior year only. Although, it occurs to me that my high school only reported my senior year's GPA. That's what HS counselors are for. Talk to yours.

**Math**

2 * 3 ?x = 5 ?y 6?x = 5?y 36x = 25y Since 36 and 25 have no factors in common, we must have x=25 and y=36

**Math-Algebra**

just write the words as math. If the tens digit is t and the units digit is u, then: t = 2u+2 10u+t = 5+3(t+u) solve for t and u

**math**

rewrite as b = -(a+1)/c b = -(1+ac) b = -(c+1)/a Now eliminate b: -(a+1)/c = -(1+ac) -(c+1)/a = -(1+ac) Now eliminate c, and you end up with a = -2 or 1

**PreCal**

since the coefficients are all real, the complex roots must come in conjugate pair. So the minimum polynomial would be y = (x-(1+?3 i))(x-(1-?3 i)) = ((x-1)-?3 i)((x-1)+?3 i) = (x-1)^2 - (?3 i)^2 = x^2-2x+1 + 3 = x^2-2x+4

**algebra**

turn the words into math: m+a = 35 2/3 m + 3/4 a = 25 now just crank it out

**algebra**

logx + logy = 6 logx - logy = 2 Now just solve as usual for logx and logy. Then raise whatever base you are using (probably 10) to the respective powers.

**Science**

3*2pi/8 = ? m/s

**satistics**

you can play around with Z table stuff here: http://davidmlane.com/hyperstat/z_table.html

**Math**

Assuming all the cards are to be used, 564 = 2^2 * 3 * 47 Looks like 2,3,6 divide 564 evenly.

**Math**

each cycle uses 6 beads, in the ratio 1:3:2 = 7:21:14 You can see that 7 cycles will use up all the reds, with others left over.

**math**

250/1200 = .2083 = 20.83%

**maths lit**

5000(0.15)(90/365) = ?

**math**

10??3

**Physics 11**

just google optics plane mirror and select "images" and you will find lots of ray diagrams

**ALGEBRA 1**

as written, you can't. If you mean -2n^2-8n+42=0 then get rid of the factor of -2, and you have n^2+4n-21 = 0 n = (-4±?(4^2+84))/2 ... Just use the formula and plug in your numbers. Sometimes it helps to factor something out, so you don't have to work with large...

**math-precalculus**

this can't be that hard. Just draw the lines. Starting at (0,0), he ends up at (-4,-2). So, how far is that?

**Algebra 1**

8a^2-a+2 = 0 x = (1±?(1^2-4*8*2)]/(2*8) = (1±?-63)/16 = (1±3?7 i)/16

**MATHS**

draw a diagram. Cut the chord in half with a radius drawn through its center. Now you can see that the radius r is r^2 = 10^2 + 12^2 If the radius is not what you want, then maybe you should have proofread your post...

**Algebra 2**

the period is 24, so y = sin(?/12 x) The temperature varies between 60 and 80, so the center-line is y=70, and the amplitude is 10 y = 10sin(?/12 x) + 70 I don't know what time the temperature is 70, but if it's at 6 am, then the horizontal shift is 6 hours, meaning y...

**Quantitative methods**

If 360 days counts as a year, then you want P such that 0.12*P = 934.20 If a year is counted as 365 days, then 0.12*(360/365)*P = 934.20

**Math**

if the number is 3xxx with x>5, then the minimum sum is 3633=15 so, that will not work If the number is 4xxx, then there must be 2 4's and 2 2's. That leaves only 4422 as a possibility.

**MATHS**

I guess if you discount B itself and Ø, then that leaves 254 "proper, non-null" subsets.

**maths**

5^(2?9) = 125^x 5^(2*3) = 125^x (5^3)^2 = 125^x 125^2 = 125^x 2 = x

**Economics(help!)**

revenue R = 60q profit P = R-C = 60q-(100+q^2) so find q such that dP/dq = 0

**math**

a+ar+ar^2 = 35 a*ar*ar^2 = 1000 now just solve for a and r.

**maths**

3xy^2 -4+2y=29 3y^2 + 6xyy' + 2y' = 0 at (1,3), we have 27+18y'+2y' = 0 y' = -27/20 So, now we have a point and a slope, so the tangent line there is y-3 = (-27/20)(x-1)

**Calc**

4xy+ln(x^2y)=7 4y + 4xy' + 1/(x^2y)(2xy+x^2y') = 0 4xy' + 1/y y' = -4y - 2/x y' = -2(2y + 1/x)/(4x + 1/y) = -2y(2xy+1) --------------- x(4xy+1) or, note that 4xy+ln(x^2y)=7 4xy + 2lnx + lny = 7 4y + 4xy' + 2/x + 1/y y' = 0 (4x+1/y)y' = -4y - 2/x...

**Calc**

x=sec(1/y) 1 = sec(1/y)tan(1/y)(-1/y^2) dy/dx so, dy/dx = -y^2 cos(1/y) cot(1/y) or, x=sec(1/y) 1/y = arcsec(x) y = 1/arcsec(x) y' = -1/[x?(x^2-1) arcsec(x)^2] you can see that they are the same, since cos(arcsec(u)) = 1/u tan(arcsec(u)) = ?(u^2-1)

**Calc**

just the good old chain rule and product rule d/dx e^u = e^u du/dx d/dx uv = u'v + uv' so, with y = x cosx + x^4 e^2x y' = (1)cosx + (x)(-sinx) + (4x^3)(e^2x) + (x^4)(e^2x)(2)

**MATHS**

arc = r? = 7(?/3) perimeter = 2r + arc

**Algebra**

h = -16t^2 + 60t = 4t(-4t+15) now work on B and C again.

**math**

since the y values differ by 0.6, and y(0)=4 y = 0.6x + 4

**Math**

very possibly, but unknown without further information.

**geometry**

reflection across what? I guess it doesn't matter, since any set of points PQRS will be transformed to some P'Q'R'S' ...

**maths**

x(x-3) = 18 Work the algebra, but it should be easy to tell which two factors of 18 differ by 3.

**Math**

40

**Math**

0x50=0 1x50=50 2x50=100 so, what do you think?

**Math**

see related questions below