# Posts by STEVE

Total # Posts: 51,750

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

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) = ?

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

Maths
w+a+b = 100 50w+10a+b = 500 The equations don't work out too well, so let's play around with some values that add up to Rs500, and see whether we can wind up with 100 fruits: (b,a,w) 90,1,8 = 500 91,1,8 = 501 50,40,1 = 500 50,30,3 = 500 Since the first line shows 99 ...

Math
r^2 = 162/18 = 9 Now you can find the 1st term, and then S8 = a(r^8-1)/(r-1)

Aptitude
draw a diagram. It will show 4 identical rectangular areas that are not paved. Find the area of one of those, multiply by 4, and subtract that from the total 1500m^2 area. That will be the area of the paved parts.

maths
a+ar = 28 ar^2+ar^3 = 252 solve for a and r, and then choose the values which make ar^6 positive

maths
a+7d = 5(a+2d) a+6d = a+3d+9 solve for a and d, and then you can write the sequence.

Math
false

Geometry
Do we assume that there is a single triangle, of fixed size, which we are manipulating? That is, its sides are of fixed length?

Calculus
if we let the base have length 20, then the altitude of the triangle is h = 15sin? so the area is a = 1/2 bh = 75sin? da/dt = 75cos? d?/dt when ? = ?/3, then da/dt = 75(1/2)(?/90) = 5?/12 m^2/s

physics
two postings, still no coherent question.

Algebra
A. factor out a 4t B,C. just plug in the value for t. C should be easy to explain if you think of what H=0 means.

Math
for the perimeters, just find the lengths of the sides and add them up. The areas are a bit trickier, but (a) once you get the sides, you will see that it is a right triangle, so the area is easy. (b) is easy, since it is easy to see that it is isosceles, with base=4 and ...

Trigonometry
1/(sin^2x-cos^2x) = 1/[(sinx-cosx)(sinx+cosx)] so, using a common denominator, 1/(sin^2x-cos^2x) - 2/(cosx-sinx) = 1/[(sinx-cosx)(sinx+cosx)] + 2(sinx+cosx)/[(sinx-cosx)(sinx+cosx)] = (1+2sinx+2cosx)/(sin^2x-cos^2x) I see several typos in your posting. If I have interpreted ...

Math
m/w = 3/7 w = m+12 ...

Physics
(5,?/2) it's right up the y-axis...

science

Math
GCD(20,30) = 10 so, 10 bags, each with 2 blueberries and 3 grapes not much of a snack, eh?

Maths
in real math, that is 14/?6 - ?5 - ?11 to get a rational denominator, multiply top and bottom by ?6, giving 14?6/6 - ?5 - ?11 = (14?6 - 6?5 - 6?11)/6

Physics 1st paper
use the law of cosines: x^2 = 8^2 + 8^2 - 2*8*8*cos(60°)

geometry
I'd say enough to cover 1000 ft^2

Calculus
?dx/(x-2) = ln(x-2) first off, ln(x-2) is not defined for x < 2. So, some like to evaluate it as ?[1,3] dx/(x-2) = ln|x-2| [1,3] = ln|3-2|-ln|1-2| = ln1 - ln1 = 0-0 = 0 That is because the graph is symmetric about (1,0) so the upper and lower areas cancel out.

Algebra
yes

Math
uh, 51 ?

Math
50

Math
well, every digit except the 8 must be 9, right?

Math
After x months they will be equal if 310-15x = 90+15x Now, try to make some effort on the other problems, ok? The idea of this site is not to do your homework assignments. We can help, but expect you to bring something to the table, especially when several problems are similar...

English
#1 not #2,3 are both ok.

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