Sunday

November 29, 2015
Total # Posts: 35,840

**MATH**

well, let's see 1=√1 2=√4 3=√9 4=√16 5=√25 So, do you still think √6 is between 4 and 5?
*October 14, 2015*

**Algebra**

-4(-3x+w)+6(-6w+2x) 12x-4w-36w+12x ...
*October 14, 2015*

**Math**

well, √(49+64) = √113 Is 5.4 still your choice? and what the heck is approxir???
*October 14, 2015*

**7th Grade Maths**

(10/1.5)*10 If she jogs 2 times as far, it will take 2 times as long, and so on. That's why the above works.
*October 14, 2015*

**college algeb**

try them yourself, and then see what wolframalpha.com does. For example, #3 is http://www.wolframalpha.com/input/?i=x^2-3x-10+%3E%3D+10
*October 14, 2015*

**calculus**

See if you can get what wolframalpha.com gets: http://www.wolframalpha.com/input/?i=%28%2818x^2-6y%28%286x^3-3y^2%29%2F%284xy%2B1%29%29%29%284xy%2B1%29+-+%286x^3-3y^2%29%284y%2B4x%28%286x^3-3y^2%29%2F%284xy%2B1%29%29%29+%29%2F%284xy%2B1%29+^2
*October 14, 2015*

**calculus**

oops. The denominator is (4xy+1)^2
*October 14, 2015*

**calculus**

3x^4-4xy^2+7=2y 12x^3 - 4y^2 - 8xyy' = 2y' (8xy+2)y' = 12x^3-4y^2 y' = (6x^3-3y^2)/(4xy+1) y" = (18x^2-6yy')(4xy+1) - (6x^3-3y^2)(4y+4xy') ------------------------------------------------------- (4xy+1) Now it's just algebra. Substitute the ...
*October 14, 2015*

**differential calculus**

Using similar triangles, if the man is x from the light, and his shadow is h tall, h/40 = 6/x 1/40 dh/dt = -6/x^2 dx/dt So, when the man is 10 ft from the light, 1/40 dh/dt = -6/100 * 4 dh/dt = -9.6 ft/s
*October 14, 2015*

**algebra**

a+5d=21 17/2 (2a+16d) = 0 The sequence is 56, 49, 42, 35, 28, 21, 14, 7, 0, ...
*October 14, 2015*

**math**

are we using linear cooling, or Newton's law?
*October 14, 2015*

**Math**

(x+4)5 = 3(x + x+2)-6 Now just find x, the smallest number.
*October 14, 2015*

**Logarithm help please**

shouldn't there be an x somewhere in the formula?
*October 14, 2015*

**Math**

5/8 x = 3/5 (x+1) x/(221-x) = 8/9 It also helps to know that 221=17*13
*October 14, 2015*

**Calculus**

huh? it's not (e^3t)^6 = (e^2t)^9 6e^3t = 9e^2t e^t = 9/6 t = log 1.5
*October 13, 2015*

**MATHS**

3x^2+3tx-xyt-t^2y 3x(x+t) - yt(x+t) that help?
*October 13, 2015*

**precalc**

Hints: sec-cos = 1/cos - cos = (1-cos^2)/cos csc^2 cos^ = (1/sin^2)cos^2 = cot^2 sin/csc = sin^2 and cos/sec = cos^2
*October 13, 2015*

**MATHS**

(2j)^-1 = 1/(2j) (p/6)^-3 = (6/p)^3 = 216/p^3
*October 13, 2015*

**Algebra**

Well, you have the rule, so you know that t(1) = 3*25 t(n+1) = t(n)*25 so, t(n) = 3*25^n
*October 13, 2015*

**Algebra 2**

50+35x = 190
*October 13, 2015*

**Algebra 2**

since x=y+2, (y+2)+2y=17 ...
*October 13, 2015*

**Math**

If you want to find x so that 2/3 > 3/x, then just multiply both sides by 3x and you have 2x > 9 Can you do that now?
*October 13, 2015*

**Calc**

well, after t hours, the plane has gone 420t miles. So, the distance z is found using z^2 = 2^2 + (420t)^2 so, that means that z is changing at 2z dz/dt = 2*420^2 t now just plug in your numbers.
*October 13, 2015*

**Math**

Just expand things, collect terms, and solve for x: 4x(x-2)=(2x+1)(2x-3) 4x^2-8x = 4x^2-4x-3 Now go for it!
*October 13, 2015*

**Algebra 2**

clearly, since 7 is subtracted for each term, An = 17-7(n-1)
*October 13, 2015*

**Algebra 2**

just multiply both sides by 5x and then go for it.
*October 13, 2015*

**Math**

a relation is not a function if one value of x maps to more than one value of y. So, which relation has unique 1st elements for all its pairs?
*October 13, 2015*

**Math**

7^-2 = 1/7^2 = 1/49 2.28x10^8 is what you wrote 2.28x10^-8 = 0.0000000228 The others look good. Watch out for those negative powers.
*October 13, 2015*

**Math**

well, 324 = 108 * 3
*October 13, 2015*

**Simple Interest**

The interest for n days is 665 * 0.099/365 * n So, figure out how many days of interest he has to pay.
*October 13, 2015*

**Math**

I agree. Of course, the mere presence of a variable does not mean it's open. 2y+3 = 2y+3 is true for any y 2y+3 = 2y+2 is false for any y
*October 13, 2015*

**precalc**

well, (1+tan)/sin = (1 + sin/cos)/sin = (cos+sin)/(sin cos) That should get you going...
*October 13, 2015*

**Geometry 1 question**

Invalid The converse is not necessarily true. There may be lots of kids dismissed early who do not play sports at all.
*October 13, 2015*

**Calculus**

well, v = at so, what is t when -16t^2 + 96t = 128? Pick the lowest value, since you want the ball on its way up. Now plug that in to find v at that time.
*October 13, 2015*

**Math**

how much work is done each hour? 1/30 + 1/40 = 1/x It will take them x hours working together. Actually, the problem is very poorly worded, since the times are for shoveling their own driveways, and we have no idea which driveway they work on together.
*October 13, 2015*

**pre-cal**

a little synthetic divsion shows that the remainder of the division is 3-k. We wan the remainder to be zero, so k=3 and we see that x^3-kx^2+x+5 = (x+1)(x^2-4x+5)
*October 13, 2015*

**pre-cal**

assuming c is real, the we also need to have x-i as a root. That means that x^2+1 must divide it. A little synthetic division shows that the remainder is c-9. The remainder must be zero, so c = 9. x^4+10x^2+9 = (x^2+1)((x^2+9)
*October 13, 2015*

**math**

I think you mean an ant weighs 2*10^-5 lbs. So, the ants weigh 2*10^-5 * 1*10^15 = 2*10^10 lbs
*October 13, 2015*

**Math**

C is the converse, and it is clearly false. 11 < 15 but 11 ~< 10 The other statements may be true or false, but they are not the converse of the given statement.
*October 13, 2015*

**achimota secondary school**

(11+x)(3)=45
*October 13, 2015*

**college algebra**

Since revenue = quantity*price, after x 1-cent reductions, the revenue is r(x) = (600+20x)(0.50-0.01x) Now use that to answer the questions.
*October 13, 2015*

**Math**

If the dimensions are x,z, with z being the height, then x^2 z = 78, so z=78/x^2 The cost c is c(x,z) = .30x^2 + 4(.10xz) + .20x^2 But, z=78/x^2, so c(x) = .30x^2 + .4x(78/x^2) + .20x^2 c(x) = .50x^2 + 31.2/x Now that's not easy to do algebraically, but with a little ...
*October 13, 2015*

**math**

each draw there are 10 marbles. So, P(pink,pink) = 3/10 * 3/10
*October 13, 2015*

**Math**

well, is it true for y=0? Is it true for y=2.5? So, ...
*October 13, 2015*

**math**

2*(m)^2*(p) 2*(-5)^2*(-4) = 2*25* -4 = -200 (-5)^2 = 25 is not the same as -5^2 = -25 Gotta watch the order of operation. powers are done first
*October 13, 2015*

**Calculus**

well, what is t when s=0? Use that value to calculate v(t) = -32t-32
*October 13, 2015*

**math**

Both look good to me.
*October 13, 2015*

**Calculus 1**

Assuming you meant x=0, g'(x) = 1/3 (1+x)^(-2/3) g'(0) = 1/3 So, the line going through (0,1) with slope 1/3 is ? See http://www.wolframalpha.com/input/?i=plot+y%3D%281%2Bx%29^%281%2F3%29%2C+y%3Dx%2F3%2B1+for+-1%3C%3Dx%3C%3D2
*October 13, 2015*

**Math**

.33
*October 13, 2015*

**math**

just get out your calculator and convert them all to decimals. Then it will be easy to sort them out.
*October 13, 2015*

**Surd help plz**

well, √59300 = √(5.93*10^4) = √5.93 * 10^2 . . .
*October 13, 2015*

**Math**

#1 is ok five times k = 5k you did k divided by 5 3t+s = 45, but 3(3t+s)=135 2s-t = 2*9-12 = 18-12 = 6 You did 2t-s
*October 13, 2015*

**Math**

No, the domain is [3,8)U(8,∞)
*October 13, 2015*

**Math**

Sarah is correct in concluding that the domain of √(2x-3) is [3, ∞). But x-8 = 0 when x=8 division by zero is not defined 8 is not in the domain, so [3, ∞) cannot be the domain, since it includes 8. So, what is the domain?
*October 13, 2015*

**Math**

10d + 25(d-4) = 600 Now just solve for d, and you can figure the rest.
*October 13, 2015*

**Mathematics**

10 fruits 5 bananas P(banana) = 5/10
*October 13, 2015*

**Maths**

recall that y' is the slope of the tangent line. The slope is the tanθ, so y'(x) = 4x^3-3x^2+7 y'(2) = 4*8-3*4+7 = 27 = tanθ θ = 87.9° The line x-2y-1=0 has slope 1/2 So, where is y' 1/2? y' = 2x-3 2x-3 = 1/2 when x = 7/4
*October 13, 2015*

**Calculus 1**

remember your trigh identities: tanh = sinh/cosh sech^2 = 1-tanh^2 and so on.
*October 13, 2015*

**Calculus 1**

sounds about right.
*October 13, 2015*

**Calculus 1**

good. just enter your expression, and it will evaluate it. Bookmark that site!
*October 13, 2015*

**Calculus 1**

what, you don't have a calculator? Or an online one, such as wolframalpha.com? I mean, geez...
*October 13, 2015*

**5th grade Math**

technically, it's 5(600+400) By moving the 5, you also tossed in a commutative property of multiplication.
*October 12, 2015*

**Math**

it is the original number. Write down your fractions, and then you can see how the factors and units cancel.
*October 12, 2015*

**MATH**

The average rate of change is change-in-y ------------------ change-in-x So, you have Between (3,11) and (6,65): (65-11)/(6-3) = 54/3 = 18 (b,m) and (s,u): (u-m)/(s-b) (x, f(x)) and (x+h, f(x+h)) [f(x+h)-f(x)]/h
*October 12, 2015*

**math**

21:(7/9) = 21/(7/9) = 21*9/7 = 3*9 = 27/1
*October 12, 2015*

**Geometry**

no, because 23 is not divisible by 3! You want B, because 27 is divisible by 3, but not divisible by 6.
*October 12, 2015*

**Logarithm help**

each year the value is 0.85 as much. So, after t years it is worth .85^t as much. So, you want t when .85^t = 0.5 Now take the log of both sides: t log .85 = log .5 t = (log .5)/(log .85) = 4.26
*October 12, 2015*

**Algebra 2**

Your product matrix is correct. p12 is the element in row 1, column 2: 6 Looks like you need to review the introductory material on matrix notation!
*October 12, 2015*

**urgent physics help**

you know that s = rθ Plug in your numbers. Remember that θ is in radians, which your value clearly is not.
*October 12, 2015*

**Math**

start off with 121 212 ----- 333 as long as there is no carry, things should work fine.
*October 12, 2015*

**math**

In that case, play around here: http://davidmlane.com/hyperstat/z_table.html You can see how it all works. It amazes me how students can get online for help, and not use the amazing resources that are available with just a little help from google.
*October 12, 2015*

**math**

so, do you have a Z table to consult? What did you find?
*October 12, 2015*

**math101**

|3x+15| < 30 case 1: 3x+15 < 30 3x < 15 x < 5 case 2: -(3x+15) < 30 3x+15 > -30 3x > -45 x > -15 so, the solution set is (-15,5), as shown here: http://www.wolframalpha.com/input/?i=|3x%2B15|+%3C+30
*October 12, 2015*

**Math**

1/8^9 or 8^-9 was there something else you wanted to do with that?
*October 12, 2015*

**College Algebra**

at time t hours after 3:00, the trains have gone 70t miles and 55(t-1) miles when they meet, 70t + 55(t-1) = 200 Now, just find t and add it to 3:00
*October 12, 2015*

**Science - Physics**

as always, the x-component of v is v cosθ. So, plug in your numbers.
*October 12, 2015*

**Math**

well, is it true for all values of x? How about x=0? 2 = 11 Nope. So, try to find a value for x which makes it true, or show that there is none at all.
*October 12, 2015*

**English grammer**

or, it could be comparing the sky after a heavy rain to the sky after a light rain. Or other stuff. But it still could be grammatically (if not actually) correct.
*October 12, 2015*

**Maths**

clearly, C = (2,√41) Since B and C are on the same vertical line (x=2), which is 5 units from (7,4), the triangle has base √41 and altitude 5.
*October 12, 2015*

**Math**

|-3| = 3 -3 = -3 3 and -3 are not the same.
*October 12, 2015*

**math**

The circles are (x-3)^2 + (y+2)^2 = 11 (x+4)^2 + (y+1)^2 = 39 So their centers are at (3,-2) and (-4,-1) The circles intersect at (73/50 ± √429/50 , -89/50 ± 7√429/50) or (1.046,-4.680) and (1.874,1.120) Now, using those two points, and knowing the ...
*October 12, 2015*

**College Algebra**

this just a parabola. You know that for ax^2+bx+c, the vertex (minimum) is at x = -b/2a. so, plug in your values of a and b to find the desired x.
*October 12, 2015*

**Physics**

well, F=ma Since the forces are equal and opposite, plug in the numbers.
*October 12, 2015*

**math**

In the usual syntax, -1/8 x^2 + 4x + 3 You should recognize that as a parabola which opens downward. Its vertex is at x = 16, which is to the right of our interval. So, the min will be at x=0 and the max will be at x=9. Incidentally, your interval should be [0,9], not (0,9). ...
*October 12, 2015*

**algebra 2**

forgot the 2nd U. Should be (-∞,-2)U(-2,2)U(2,∞)
*October 12, 2015*

**algebra 2**

think about it. You want (-∞,-2)U(-2,2)(2,∞) You have duplicated some intervals and overlapped them.
*October 12, 2015*

**Math**

how about some parentheses, so we can tell what the denominator is?
*October 12, 2015*

**Calculus**

the quadratic formula is your friend. use it.
*October 12, 2015*

**functions and trig**

x^3 -> (x-4)^3 -> -(x-4)^3
*October 12, 2015*

**Math Pre-Algebra HELP**

#1. Well, you could actually try plotting the point and rotating the paper. Clearly, (0,-2) -> (-2,0) Being a vertex of a square is just noise -- makes no difference in the rotation. #2 garbled
*October 12, 2015*

**8th Grade Pre-algebra**

#3 A? Really? Is 42 between 1 and 10? B,C,D are all SN. #4 A (2.0 x 10^4)(3.0 x 10^3) = (2.0)(3.0) x (10^4*10^3) = 6.0 x 10^7 #5 C Remember the distributive rule? ac + bc = (a+b)c (7.0 x 10^6)+(2.0 x 10^6) = (7.0+2.0)x10^6 = 9.0x10^6 You clearly need to study up on the rules ...
*October 12, 2015*

**8th Grade Pre-algebra**

just remember that in SN, a number is written in two parts: N x 10^p where 1.0 <= N < 10.0 p is an integer With that in mind, what are your choices?
*October 12, 2015*

**Mabel hill, physics**

force resultant: 4i+3j equilibrium force: -(4i+3j)
*October 12, 2015*

**math**

well, v(t) = -32t solve for t in 256 - 16t^2 = 0
*October 12, 2015*

**Mathematics**

p-4 = q-p q-p = 13-q Now just solve for q and p Or, note that there are two equally-spaced terms between 4 and 13. So, the difference (13-4) is divided into three equal parts. That should help.
*October 12, 2015*

**modern geometry**

Hmmm. I'm still struggling to figure out the question!
*October 12, 2015*

**Mathematics**

a+7d = 18 a+11d = 26 Now you can find a and d, and any other terms.
*October 12, 2015*

**8th grade pre-algebra**

#30 Your answer is fine, but line 3 has a spurious "-" in -27. Either it was a typo, or you lost it by accident. In any case, 3^-3 = 27, not -27. Your other syntax is also mangled. 1/((3^-3)(x^-6)) = 1/(1/27 x^-6) = 27x^6 Your mixing up fractions and negative ...
*October 12, 2015*

**math**

yes -- each x is related to a single y value. No vertical line crosses the graph in more than one place.
*October 12, 2015*

**math**

Nope. Draw the quadrants. QI is where things are simplest: x>0 and y>0. That is the upper right. Then, the quadrants are numbered counter-clockwise. google is your friend. use it. It will show lots of images, all neatly labeled.
*October 12, 2015*