# 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**

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) = ?

**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**

google is your friend: https://www.google.com/search?q=hachure+line+inside&ie=utf-8&oe=utf-8

**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.