Monday

December 5, 2016
Total # Posts: 46,807

**Algebra2**

thank you

*November 15, 2016*

**Algebra2**

Which correctly describes the roots of the following cubic equation? x^3-5x^2+3x+9=0

*November 15, 2016*

**math**

3500 * e^(.04*3)

*November 15, 2016*

**Calc**

why not just use x? f(x) = 2secx+tanx f' = 2secx tanx + sec^2x = sec^2(x) (2tanx/secx+1) = secx^2(x) (2sinx+1) critical numbers are where sec^2(x) = 0 -- no solutions there sinx = -1/2 -- x = 7?/6, 11?/6

*November 15, 2016*

**math**

433/(433+424) Actually, that is just the probability that they answered "yes." They may have been lying...

*November 15, 2016*

**Calculus**

typo alert dy/dt at y=2.5 is -1/160, not -1/120

*November 15, 2016*

**Calculus**

When the water is 2.5m deep, the section draining is just a rectangular prism with area 160m^2 and height 1/2 m. So, draining at 1m^3/min, the water level is dropping at a rate of 1/120 m/min When the water is y m deep (y<2), the side cross-section of the pool is a right ...

*November 15, 2016*

**math**

10*6, right?

*November 15, 2016*

**maths need help word problem**

a+b=9 (10b+a)/(10a+b) = 6/5 54/45 = 6/5

*November 15, 2016*

**Algebra**

nope. 9x+3y = -22 has slope -3 better review how to find the slope.

*November 15, 2016*

**Math**

6/(6+7)

*November 15, 2016*

**Math**

come on -- just add them up

*November 15, 2016*

**Math grade 6, Fractions**

64-28=36 stickers that Dan gave Perry 36 is 4/5 of the original amount so, 9 is 1/5 Thus Perry had 45 to start with

*November 15, 2016*

**maths**

the 2nd pole is 20m away the 3rd is 40m and so on

*November 15, 2016*

**Maths**

9,999 and 10,000

*November 15, 2016*

**wisdom'**

and threw up

*November 15, 2016*

**math**

w(3w-2) = 65 what are the factors of 65?

*November 15, 2016*

**Math**

subtracting less means the result will be greater

*November 15, 2016*

**Maths**

Suppose 4 of each color were drawn. That makes 16 balls. The 17th ball would have to be the 5th of one of the colors.

*November 15, 2016*

**math**

if you say so. tan(75/2) = (1-cos75)/sin75 now, 75 = 90-(30/2) so, use the half-angle formulas on that

*November 15, 2016*

**College Algebra**

left: y = (x+4)^3 up: y = (x+4)^3 + 8 scale: y = 0.75((x+4)^3 + 8) = (3/4)(x+4)^3 + 6 = (3/4)x^3 + 9x^2 + 36x + 54

*November 15, 2016*

**Arithmetic**

.20 * 29.50

*November 15, 2016*

**Math**

man - just use the formula! Prt = 4010 * .052 * 4

*November 15, 2016*

**geometry**

see previous post for method.

*November 15, 2016*

**geometry**

well, the central angle is the same as the exterior angle... Or, you have an isosceles triangle with vertex of 60. The interior angles are made up of two of the triangles' base angles.

*November 15, 2016*

**Chemistry**

see the related questions below

*November 15, 2016*

**Algebra**

note that y changes by 2 when x changes by 1.

*November 15, 2016*

**Math**

10096

*November 15, 2016*

**math**

in 4 days, A&B&C did 4(1/24 + 1/36 + 1/48) = 13/36 of the job In the last 3 days, B working alone did 3/36 = 1/12 of the job That left A&B to do 5/9 of the work 1/24 + 1/36 = 5/72, so it took A&B 8 days to do their part.

*November 15, 2016*

**math**

none of the above, that's for sure.

*November 15, 2016*

**Chemistry**

google is your friend. And it's faster than waiting around here.

*November 15, 2016*

**College Calculus**

20 * (1/2)^(t/27)

*November 14, 2016*

**Math : )**

1/6 + 1/3 = 1/2 red or blue 3/7 * 1/2 = 3/14 green 3/14 x = 27 x = 126 21 red 42 blue 27 green

*November 14, 2016*

**Tim**

oh please - just use their definition! f2(x) - f3(x) = (1/8 (x+16)^2-98) - (2x+24) You might want to simplify that to x^2/8 +2x -90

*November 14, 2016*

**Tim**

no idea what you want to do. We could make g(x) = f2(x) - f3(x) or whatever you want to do. What do you mean when you say "this function"?

*November 14, 2016*

**math**

no files here. Surely you can compare two numbers!!???!?

*November 14, 2016*

**Math**

pieces: x x/2 x/2+4 x + x/2 + x/2+4 = 10 2x = 6 x = 3 check: 3 + 1.5 + 5.5 = 10 How did they come up with 2 3/4? I suspect a typo. f(-1/2) = 2(1/4) - 1/4 - 4 = -15/4

*November 14, 2016*

**Geometry**

Pair up the sides. You will find that the three sides of the two triangles match up, so since the two triangles have matching sides, they are congruent: SSS

*November 14, 2016*

**Algebra**

x + 2x+3 = 51

*November 14, 2016*

**maths**

40 spaces, so 41 poles. I think you can gt (c). Figure out how far the nth pole is.

*November 14, 2016*

**maths**

well t wholes is 24/24 So what do you add to 7 to get 24?

*November 14, 2016*

**Math**

and have someone seal the edges tightly with duct tape. Soon your pain will be gone.

*November 14, 2016*

**College algebra**

you have to multiply by 1/2 every 1500 years. So, the fraction remaining after t years is (1/2)^(t/1500) So, after 2800 years, the fraction remaining is (1/2)^(2800/1500) = 2^-1.8667 = 0.2742 = 27.42% Note that 2800 is almost 3000, or two half-lives. At t=3000, 1/2^2 = 1/4 = 0...

*November 14, 2016*

**Math**

Start with T1 which has sides 1 and 1. Its hypotenuse is ?2 Now draw T2, with its base as the hypotenuse of T1, and its other side is 1. T2 has sides ?2 and 1, so its hypotenuse is ?3 Keep drawing new triangles on the hypotenuse, and you will get a spiral figure. Tn has its ...

*November 14, 2016*

**Math checking answers (Calculus Differentials)**

I got the same answers. I hope we're both right!

*November 14, 2016*

**Algebra**

since the flat fee is less than the hourly fee, the more hours, the more pay.

*November 14, 2016*

**Algebra**

since the number of hours worked is the same, of course adding another $50 fee will pay more.

*November 14, 2016*

**true**

If the 4-vector is <4,0> then the 3-vector is <3/?2,3/?2> Add 'em up.

*November 14, 2016*

**Math**

surely you can find two small primes that work in each case... For example, 12 = 5+7 38 = 7+31

*November 14, 2016*

**science**

convert the mass to moles. Each mole of Zn requires 2 moles of HCl. So, determine which reagent will run out first. That will tell you how many moles of products get formed. Each mole of Zn used produces 1 mole of H2. Convert that back to grams.

*November 14, 2016*

**Math**

each side will be ?216 If you can't figure that out, just start listing the cubes of integers: 1^3 = 1 2^3 = 8 3^3 = 27 ... and see where you get 216

*November 14, 2016*

**Trigonometry**

csc x < 0 in QIII,QIV cot x > 0 in QI, QIII So, all 180 < x < 270 satisfy the requirements.

*November 14, 2016*

**Math**

what is /25? -25 + -9 = -34 25 + -9 = 16

*November 14, 2016*

**Geometry**

looks good

*November 14, 2016*

**Graphing Linear Equations and Inequalities**

well, did you fill in the table? when x=0, you have 4y = -16 and so on

*November 14, 2016*

**Maximal area and dimensions of a window**

see the related questions below. It does get a bit messy.

*November 14, 2016*

**Calculus - Word Problems**

v = 4/3 pi r^3 dv/dt = 4 pi r^2 dr/dt Now just use your numbers

*November 14, 2016*

**Calculus - Optimization**

blah blah stop reposting and wasting everyone's time

*November 14, 2016*

**Calculus**

see related questions below

*November 14, 2016*

**Algebra 2**

Take a look at the graph and figure it out. http://www.wolframalpha.com/input/?i=x%5E3%2B3x%5E2-9x-8

*November 14, 2016*

**math**

cosines will work well here, since you have B,a,c b^2 = a^2+c^2-2ac*cosB Then you can use sines to get A,C,b

*November 14, 2016*

**math**

You have a and A, so use sines: a/sinA = b/sinB That gives you B. Now A+B+C=180 Having C, use sines to get c.

*November 14, 2016*

**math**

I could not get the image to come up, but you will find that the maximum area is achieved when it is equally split among the widths and lengths. So, 1050 will be divided among the vertical pieces, and 1050 will be split into horizontal pieces. Define the 2100 as the sum of *x...

*November 14, 2016*

**math**

I will assume you gave the correct numbers. Now, present them in a way we can understand. Copy/paste from spreadsheets and word processor files does not work well here.

*November 14, 2016*

**Math**

construct a segment of length 19.5 At each end, draw a circle of the same radius. Where the circles intersect above (or below) the line will be the third vertex of the triangle, since all three sides are the same. Get out your protractor and measure the angles.

*November 14, 2016*

**Math**

a set has individual members Usually finding part of a whole involves dividing a single unit into pieces. Not really so different, but I think of it as the difference between cutting up an apple and separating the pieces of a puzzle.

*November 14, 2016*

**math**

Looks like Heron's formula is best here to get the area. Then, divide that by 70m^2/gal to get the # gallons.

*November 14, 2016*

**math**

so, a total of 16 east 8 north Now just find the length of the hypotenuse.

*November 14, 2016*

**Math**

depends on how long it is to take. 51 mph will do the job in an hour.

*November 14, 2016*

**Math**

1 - 1/5 = ? What did he spend it on -- Capital Letters?

*November 14, 2016*

**math**

and ... ?

*November 14, 2016*

**pascal programming**

the only critical thing here is deciding the age of the division.

*November 14, 2016*

**math**

x[(1.12)^(3/2) - (1.12)] = 150 assuming compounding annually

*November 14, 2016*

**math**

Draw a diagram and review your basic trig functions. It should be clear that the height is 15 sin60° + 8 sin30°

*November 14, 2016*

**Calculus**

Looks good to me, but I'd write it as -7/12 ft/s

*November 13, 2016*

**Calculus**

x^2+y^2 = 25 x dx/dt + y dy/dt = 0 So, find y when x=7, and then just use your numbers to find dy/dt

*November 13, 2016*

**Graphing Linear Equations and Inequalities**

while in this case, the explanation gives the right area, technically, the area to the right of the line is x > y/2 Since the y-coordinates are measured vertically, you should be looking for the area below the line. In this case, it's the same area.

*November 13, 2016*

**Math**

x+y+z = 7900 .05x + .11y + .15z = 965 z = x+y + 500

*November 13, 2016*

**Math**

The two roots of 2 and 5 mean y = a(x-2)(x-5)(x-h) for some h. Since y(0)=10, a(-2)(-5)(-h) = 10 ah = -1 Now, fix the bogus (-4) point and see what a and h have to be.

*November 13, 2016*

**Science (galaxies and universe)**

since it takes light some time to arrive at earth, we see what was happening when it left the galaxy, not now. So, if the star is one light-year away, when we see the light, it shows what was happening one year ago. Time travel!

*November 13, 2016*

**Math**

y-k = f(x-h) translates the graph y=x by the amounts h right and k up. y = (x+2)^2-3 y+3 = (x+2)^2 y-(-3) = (x-(-2))^2 so, that is the graph y=x^2 shifted -3 up and -2 right. Or, more simply, 2 left and 3 down. Work the others the same way. You can verify your results at the ...

*November 13, 2016*

**Stoichiometry**

First, balance the equation: 2Al + 3Cl2 -> 2AlCl3 So, you need 3/2 as many moles of Cl2 as you do Al.

*November 13, 2016*

**Integral Calculus**

The p+2 just confuses things. Let q = p+2. Then you have the series 1/1 - 1/2^q + 1/3^q - 1/4^q The alternating series test says this converges for q>0 That is p > -2

*November 13, 2016*

**Math**

which multiple of 3 is 10 more than the same multiple of 2? 3x = 2x+10 x = 10 So, 10 students, 30 pencils.

*November 13, 2016*

**Math**

101 102 ... 198 199 and so on up to 904

*November 13, 2016*

**English**

#10 should be: Whoa! Bogus, D00d!

*November 13, 2016*

**PreAp Math - incomplete**

a. no way to tell, without knowing how many members in the club, or how many times they went shopping in a year. All we know is that some people spent about $18*1.055 each. Big deal.

*November 13, 2016*

**Science-please help**

2 and 3 are both involved. If the moon stood still (like the sun) #2 would do it If the earth did not rotate, #3 would still cause the moon to appear to rise and set, but it would only do it once a month, instead of once a day. I think #2 is the best answer here.

*November 13, 2016*

**Math**

think about C. It differs from B only in the rate of growth. (100% vs 3%)

*November 13, 2016*

**help me calculus**

I'll just use t for ease of typing. Those big Øs just distract me from the math. And that's "pi" not "pai" or "pie" or a dozen other ways it gets misspelled! x = cos(2t) y = 1+sin(2t) dy/dt = 2cos(2t dx/dt = -2sin(2t) dy/dx = dy/dt...

*November 13, 2016*

**NO**

?7 is real, but not an integer.

*November 13, 2016*

**Math**

assuming you meant the line joining those two points, it is (y2-y1)/(x2-x1) = (6-(-5))/(-4-3) = 11/-7 or, more usually, -11/7

*November 13, 2016*

**8th Grade Pre-Algebra**

P' = 1/3 P reflection in the y-axis just changes the sign of all the x-values. Since P" ? P', and P' is smaller than P, P" cannot be ? to P It is, however, similar to P.

*November 13, 2016*

**MATH**

clearly not A. 1.5 is real, but not an integer.

*November 13, 2016*

**another please help me check~calculus maths**

see related questions below.

*November 13, 2016*

**College algebra**

if x at 10%, then the rest (2500-x) at 8%. So, add up the interest: .10x + .08(2500-x) = 2200 But before trying to solve that, think on the numbers. No way could $2500 produce $2200 in interest...

*November 13, 2016*

**Calculus**

I guess you did. y' = (8e^(8x))(e^(8x)+9)-(e^(8x))(8e^(8x)) ------------------------------- (e^(8x)+9)^2 = 72e^(8x)/(e^(8x)+9)^2 You can use wolframalpha.com to confirm your results: http://www.wolframalpha.com/input/?i=...

*November 13, 2016*

**Calculus**

f = x^3+8x-3 f' = 3x^2+8 f'(6) = 116 dx/df = 1/(df/dx) = 1/116 1/11 must be a typo. http://www.sosmath.com/calculus/diff/der08/der08.html

*November 13, 2016*

**Algebra 2**

the real solutions are where the graph crosses the x-axis. That is, where ax^2+bx+c = 0

*November 13, 2016*