Wednesday

May 27, 2015

May 27, 2015

Total # Posts: 30,069

**algebra**

any horizontal line has equation y = c , where c is the y element of your given point so y = -3 or, the long way: slope of a horizontal line is 0 , then y = 0x + b plug in the given point(5,-3) -3 = 0(5) + b b = -3 y = 0x - 3 y = -3
*May 12, 2015*

**Algebra**

f(x) = 3x - 1 f(0) = 3(0) - 1 = -1 f(3) = 3(3) - 1 = 8 f(z) = 3z - 1
*May 12, 2015*

**Math**

2(x+2)+4x-10x use distribution for the first part = 2x + 4 + 4x - 10x now combine like terms = -4x + 4
*May 12, 2015*

**math**

(2^2)(2^8) = 2^10 so B is the correct answer
*May 12, 2015*

**No - math help please**

It asked for the coefficient of x, which is -7 What you gave is the coefficient of x^2 the correct answer is D
*May 12, 2015*

**Math**

btw, I have a typo, the equation should have said: ax + by + c = 0
*May 11, 2015*

**Math**

Little tricks that can come in handy ... For a linear equation ax^2 + bx + c = 0 the slope is -a/b so the slope of the given line is -3/-2 = 3/2 thus the slope of the new line must be -2/3 But your choice of D has a slope of 3/2, so it can't be D so write the given choices...
*May 11, 2015*

**math**

C) So in effect, the radius of one revolution is 42 cm, and one rotation is 84pi. Multiply 84pi by the number of rotations
*May 11, 2015*

**math**

use the property: ln(e^x) = x 2 = 1 e^(kt) ln 2 = kt t = ln2/k , replace k with the given value
*May 11, 2015*

**maths**

a = 1 , r = -4 you are showing 6 terms, so sum(6) = a(r^6 - 1)/(r-1) = 1((-4)^6 - 1)/(-4-1) = 4095/-5 = -819
*May 11, 2015*

**Pre-calculus ( Absolute value)**

you might plug in x = 5, but x=5 does not satisfy the equation, so it is not a solution. So what if both sides are positive. We know by definition that x-1 > 0 or x>= 1 7+3x = x-1 or -7-3x = x-1 2x = -8 or -4x = 6 x = -4 or x = -3/2 subbing either one of these does not ...
*May 10, 2015*

**math**

... at a rate of 5 inches/hr sounds like a linear rate of change. I will assume that the radius is changing at that rate V = (4/3)pi r^3 dV/dt = 4pi r^2 dr/dt dV/dt = 4pi(100)(5) = 2000pi cubic inches/hr
*May 10, 2015*

**maths**

= 2sqrt(5) - sqrt(5) + 3sqrt(5) = 4sqrt(5)
*May 10, 2015*

**Trigonometry**

RS = (1/2)(cosacosb + sinasinb - (cosacosb - sinasinb) = (1/2)(2sinasinb) = sinasinb = LS
*May 10, 2015*

**Probability**

the second differences are a constant so the relationship is quadratic. the the equation be y = ax^2 + bx + c when x = 1 a+b+c = 20 when x=2 4a+2b+c = 17 when x = 3 9a+3b+c = 13 subtract 1str from 2nd 3a+b=-3 subtract 2nd from 3rd 5a + b = -4 now subtract those last two: 2a...
*May 10, 2015*

**Maths**

the angle between the two directions is 162-25 or 137 Use the cosine law, let the distance between them be d d^2 = 10^2 + 6^2 - 2(10)(6)cos137 = ...
*May 10, 2015*

**Linear Functions**

sketch somethink like y = 2x + 3 (m>0, b>0 ) and see what you get
*May 9, 2015*

**Linear Functions**

e = .04s + 200 see which of your choices match that
*May 9, 2015*

**Math**

(I don't have my calculator with me, so I will describe the method) - find the length of the diagonal of the base using Pythagoras - take half of that length (the midpoint of the base) - use tan^-1 (147/half-length of diagonal)
*May 9, 2015*

**college precalculus I still dont get it**

To be an arithmetic sequence, the difference between any term and its previous term is a constant. e.g. 3, 5, 7, 9 , ... the common difference is 2 To be geometric, if you divide any term by its previous term you will get a common ratio, e.g. 3, 12, 48, ... 12/3 = 4, 48/12 = 4...
*May 9, 2015*

**math**

a) exclude the case where none are cracked Prob(none are cracked) = C(30,0)(.05)^0 (.95)^30 = .... b) follow the above pattern to get Prob(none) + prob(one broken) + prob(two broken) = ..... + C(30,1) (.05)^1 (.95)^29 + .... = ....
*May 9, 2015*

**algebra**

go with Steve, I messed up, right side is .60(20)
*May 9, 2015*

**algebra**

amount of 40% stuff --- x L amount of 85% stuff --- 20-x L .4x + .85(20-x) = .60x
*May 9, 2015*

**Calculus(URGENT PLS!!!)**

how about -e^cosx + c (differentiate it to test my answer)
*May 8, 2015*

**Calculus - Derivative**

2x + r(y)^(-1/2) dy/dx = x dy/dx + y dy/dx (r(y)^(-1/2) - x) = y - 2x dy/dx = (y - 2x)/(r(y)^(-1/2) )
*May 8, 2015*

**Math - Polynomials**

1. The way you typed it should give us 15g + 10k 2. D 3. B Hope you weren't just guessing
*May 8, 2015*

**maths**

the difference between 17^2 and 13^2 is 120. the next perfect square is 121 So we have to add 1
*May 8, 2015*

**7th grade math (probability)**

1-3 are correct #4. you should have divided 4 by 1/6 to get 24 "3" was the event, it happened 4 times, so 4 is the important number last one , I did not check the actual entries, but there are 24 of them
*May 8, 2015*

**Calculus**

here is a picture of what we are doing http://www.wolframalpha.com/input/?i=plot+y%3D+x%5E%281%2F3%29+%2C+y+%3D+x%2C+y+%3D+1 clearly y = x and y = x^(1/3) intersect at (0,0) and (1,1) so outer radius = R = x-1 -->R^2 = x^2-2x+1 inner radius = r = x^(1/3) - 1) --> r^2 = x...
*May 7, 2015*

**Calculus**

V = π∫(y^2) dx from a to b = π∫x^4 dx from 0 to 3 = π[x^5/5] from 0 to 3 = π(243/5 - 0) = 243π/5 cubic units
*May 7, 2015*

**maths**

I see a common factor of 10^7 (5x10^7)+(2.3x10^7) = 10^7(5 + 2.3) = 7.3 x 10^7 your answer should have said 73 x 10^6 In general a number in scientific notation should be a number between 1 and 9 multiplied by a power of 10 so 73 x 10^6, although correct in its value, is not ...
*May 7, 2015*

**Math Please Check My Answer**

From you data it looks like you made 69 choices, thus prob(pink) = 36/69 = 12/23 prob(brown) = 33/69 = 11/23 comparing: theoretical prob(pink) = .5125.. experimental prob(pink) = .5217 not bad
*May 7, 2015*

**Math**

let the base be x by x cm let the height be y xm Volume = (1/3) r^2 h = 216 r^2 h = 648 h = 648/r^2 pick any r, let's say r = 10, then h = 648/100 = 6.48 cm pick x = 12 cm, then h = 648/144 = 4.5 cm As you can see, there is not enough information. as it stands the ...
*May 7, 2015*

**XD**

Suppose it took Alice 4 hrs, when she finished Alice went at 6 km/h Becky went 16 km at 4 km/h Caitlin went 12 km at 3 km/h So for Becky to finish her remaining 8 km would take an extra 2 hrs, but in 2 hrs Caitlin only went 6 more km of her remaining 12 km, so she still has 6 ...
*May 6, 2015*

**XD**

So the total water they have is 2 + 1 3/4 gallons = 15/4 gallons or 3.75 gallons So in effect 3.75 gallons cost $2.00 1 gallon would cost 2/3.75 = .53... so James should receive 2(.5333...) or $1.07
*May 6, 2015*

**Calculus**

did you find their points of intersection? x^2 - 2x = x+4 x^2 - 3x - 4= 0 (x-4)(x+1) = 0 x = -1 or x = 4 effective height of region = x+4 - (x^2 - 2x)= 3x + 4 - x^2 area = [integral] (3x + 4 - x^2) dx from -1 to 4 = [(3/2)x^2 + 4x - (1/3)x^3] from -1 to 4 I will leave the ...
*May 6, 2015*

**Pre-Calculus**

1-|200+||-2|(-5)^3|| 1-|200+||-2|-125|| = 1-|200+||-2(125)| = 1-|200+||-250| = 1 - |200 + 250| = 1 - 450 = -449 I think your |'s are confusing
*May 6, 2015*

**algebra--1 question**

This is called the factor theorem. If the division by some binomial leaves a remainder of zero, then that binomial is a factor the same is true for numbers. e.g. 12÷3 = 4 with Remainder of 0 so 3 is a factor of 12 12÷5 = 2 with remainder of 2, so 5 is NOT a ...
*May 6, 2015*

**Calc**

How do you expect us to know what "table of integrals" you are using ? It is up to you to find the pattern of the given question in your tables.
*May 6, 2015*

**Math**

for the mean, add them up and divide by 5 for the sd: take the difference between each of the data values and the mean and square that result repeat for all 5 of them add them up, divide by either 5 or 4 depending on the definition of sd you are using, take the square root. ...
*May 6, 2015*

**Algebra**

term4 = a+3d = 15 term10= a+9d = 39 subtract them 6d = 24 d = 4 in a+3d = 15 a + 12 = 15 a = 3 term40 = a+39d = ... sum40 = (40/2)(2a + 39d) = ...
*May 6, 2015*

**Trig**

if sinA = 12/13, and since the since is + A must be in II using our standard 5-12-13 triangle, cosA = -5/13 if sinB = -7/25, to state -90 ≤ B ≤ 90 is ambiguous, since you could be on the right or the left of the y-axis I will assume B is in III , (could be in IV) ...
*May 6, 2015*

**math**

cost of 6 vans at the end of 4 yrs = 148800 i = .03 n = 4(4) = 16 P(1.03)^16 = 148800 solve for P
*May 6, 2015*

**Math Help**

the parabola is vertical, and opens downwards standard form x^2 = 4py but vertex is (-1,2) (x+1)^2 = 4p(y-2) but p = -2 (x+1)^2 = -8(y-2) (x+1)^2 = -8y + 16 8y = -(x+1)^2 + 16 y = (-1/8)(x+1)^2 - 2 for the 2nd , use y^2 = 4px and follow the above steps
*May 6, 2015*

**Calculus**

y ' = sec^2 ((1 - x)^(1/2) ) (1/2)(1-x)^(-1/2) (-1) clean it up to whatever level you need it simplified.
*May 6, 2015*

**Calc 1**

f ''(x) = 6+cosx f '(x) = 6x + sinx + c f (x) = 3x^2 - cosx + cx + k f(0) = 1 0 - cos 0 + 0 + k = 1 -1 +k= 1 k = 2 so f(x) = 3x^2 - cosx + cx + 2 f(7π/2) = 0 3(7π/2)^2 - cos(7π/2) + (7π/2)c +2 = 0 solve for c, plug into the f(x) equation and you...
*May 6, 2015*

**Math/algebra**

ok, then you know f + t = 70 or t = 70-f recall that the equation said: 5f + 10t = 595, which we reduced to f + 2t = 119 replace t with 70-f f + 2(70-f) = 119 f + 140 - 2f = 119 -f = -21 f = 21 so she has 21 fives. Can you take it from there ?
*May 5, 2015*

**Math**

several ways: if x = (2 ± √5)/3 then the factors are (x - (2 +√5)/3) and (x - (2 - √5)/3) then (x - (2 +√5)/3)(x - (2 - √5)/3) = 0 ( x - 2/3 - √5/3)(x - 2/3 + √5/3) = 0 x^2 - 2x/3 + x(√5/3) - 2x/3 + 4/9 - 2√5/9 - x&#...
*May 5, 2015*

**Math**

e.g. in 5x^2 + 7x - 18 a=5 b=7 c=-18 Your question is poorly worded a stands for the coefficient of the x^2 term b stands for the coefficient of the x term c stand for the constant
*May 5, 2015*

**math**

let the total be x A got (3/7)x = 3x/7 B got (2/3)(3x/7) = 6x/21 = 2x/7 C got 3x/7 - 49 3x/7 + 2x/7+ 3x/7 - 49 = x times 7 3x + 2x + 3x - 343 = 7x x = 343 A has 147 B has 98 C has 98 ratio of B:C = 1:1
*May 5, 2015*

**Math**

you are saying there are 3 points on the graph, but the table shows 4 points. mmmhhh? anyway: take the slope of all possible pair of points, what do you get ?
*May 5, 2015*

**Algebra**

f stands for the number of $5 bills, so by saying f = 5, you are saying there are five $5 bills. It does not say that anywhere ---------- let f be the number of fives let t be the number of tens so the VALUE of our fives = 5f and the VALUE of our tens = 10t 5f + 10t = 595 ...
*May 5, 2015*

**Math - 7th grade**

Good job, I agree with all your answers
*May 5, 2015*

**Calc 1**

let the point of contact be (x,y) or (x, -6sinx) Then for a tangent, slope = m = (-6sinx - 0)/(x-0) = -6sinx/x m = (-6sinx - 0)/(x-0) = -6sinx/x dm/dx = (x(-6cosx - (-6sinx))/x^2 , by quotient rule = 0 for a max/min -6xcosx + 6sinx = 0 xcosx - sinx = 0 xcosx = sinx x = sinx/...
*May 5, 2015*

**Math**

You are using the word "combinations" so it would be C(5,3) or 10 of them e.g. suppose you have A, B, C, D, E kind of trees ABC ABD ABE BCD BCE CDE ADE ACE BDE ACD
*May 5, 2015*

**math**

To form a triangle, the sum of any two sides must be greater than the remaining third side checking for a) is 17+13> 2 ? Yes is 17+2 > 13 ? Yes is 13+2 > 17 ? NO So 17,13,2 cannot form a triangle Repeat for the others.
*May 5, 2015*

**Algebra Readiness**

actually the correct table is C e.g. look at the first one x = -5 y = -5 - 6 = -11 try the others.
*May 5, 2015*

**math**

So the angle between them is 72° They both travel for 2 hours, so the 1st went 30 km, and the 2nd went 4 km This is just a cosine law question .... x^2 = 30^2 + 4^2 - 2(4)(30)cos72 = 841.83.. x = appr 29.01 km or, using the fact that the 2nd boat was directly north of the ...
*May 5, 2015*

**Math**

That would only be true if the height is equal to the radius
*May 5, 2015*

**Algebra (Slope)**

parallel lines have equal slopes, so slope = (6-4)/(2-3) = -2
*May 5, 2015*

**Maths**

I did this for you Always check back before reposting the same question.
*May 5, 2015*

**Analytic Geometry**

let the new point be (x,y) I will assume you mean XZ = 4XY by simple ratio: for the x's (x+1)/(4+1) = 4/1 x+1 = 20 x = 19 for the y's (y-2)/(11-2) = 4/1 y-2 = 36 y = 38 Z is (19,38) check: XY = √(5^2 + 9^2) = √106 XZ = √(20^2 + 36^2) = √1696 = 4...
*May 5, 2015*

**algebra**

speed of freigh --- x speed of passenger ---- x+6 time for passenger to go 330 miles = 330/(x+6) hrs time for freight train to go 300 miles = 300/x hrs but the times are the same 330/(x+6) = 300/x 330x = 300x + 1800 30x = 1800 x = 60 state the conclusion
*May 5, 2015*

**Geometry**

By definition of "obtuse", one of the angles must be greater than 90 So if all 3 angles would be obtuse, their sum would be greater than 270° But we know that the total sum of all 3 angles = 180° So, silly conclusion. As a matter of fact , a triangle can have...
*May 5, 2015*

**math**

nice problem: b) the easiest, just sub in (5,5) to show it works a) since y = 7x, sub the y into the circle equation x^2 + (7x)^2 = 50 x^2 + 49x^2 = 50 x^1 = 1 x = ± 1 if x=1 , y = 7 , call that A(1,7) if x = -1 , y = -7 , call that B(-1, -7) c) slope AC = (5-7)/(5-1...
*May 5, 2015*

**Maths Problem**

let the side of the larger square be x let the side of the smaller square be y 1. x^2 + y^2 = 65 2. y > 1/2x 2y > x initial thought: 65 must be sum of 2 squares, 8 and 1 immediately come to mind but 2(1) is not greater than 8 how about 7 and 4 ? is 7^2 + 4^2 = 65 ? YES ...
*May 5, 2015*

**geometry**

Which sides are parallel ?
*May 5, 2015*

**math**

i = .0825 n = 6 amount = 27000(1.0825)^6 = .....
*May 5, 2015*

**math**

number of total choices = 3 x 3 x 2 = 18 number of choices with yellow or green tofu and tea = 3 x 2 x 1 = 6 prob(stated event) = 6/18 = 1/3
*May 5, 2015*

**college precalculus**

i = .06/12 =.005 n = 8(12) = 96 P(1.005)^96 = 2000 solve for P
*May 5, 2015*

**trigonometry**

Clive probably meant: (1+sin 2A)/cos 2A = (cosA + sinA)/(cosA - sinA) LS = (sin^2 A + cos^2 A + 2sinAcosA)/(cos^2 A - sin^2 A) = (cosA + sinA)/( difference of squares) = ... I am sure you can take it from there
*May 5, 2015*

**Algebra**

original: 10 cm by 20 cm after cutting x cm at the corners new length = 20 - 2x new width = 10 - 2x height = x volume = x(10-2x)(20-2x) , 0 < x < 10
*May 4, 2015*

**math**

B worked for all of them when I tried it.
*May 4, 2015*

**math**

I would try subbing in the points e.g. (0,5) works in A,B, and D only (1,4) works in B try if the others work in B well ???
*May 4, 2015*

**math**

If it even works, the largest number must be the hpotenuse, so e.g. R is 26^2 + 20^2 = 46^2 ? test the others.
*May 4, 2015*

**math**

height/30 = sin60 height = 30sin60 = ....
*May 4, 2015*

**math**

2 fracture each third ?? I have no idea what that means.
*May 4, 2015*

**Math**

1. f(x) = x^2 - 3x + 2 for f(-2), put in -2 wherever you saw an x f(-2) = (-2)^2 - 3(-2) + 2 = 4 + 6 + 2 = 12 you are correct 2. correct again.
*May 4, 2015*

**math 0312**

speed in still water ---- x rate upstream = x-9 , where x is clearly > 9 rate downstream = x+9 17/(x+9) + 17/(x-9) = 13 times (x+)(x=9) or x^2 - 81 17(x-9) + 17(x+9) = 13(x^2 - 81) 17x - 153 + 17x + 153 = 13x^2 - 1053 13x^2 - 34x - 1053 = 0 x = (34 ± √55912)/26...
*May 4, 2015*

**Math 222**

is that g(x) = √x - 1 or g(x) = √(x-1) ? make a table of values, pick some x's , find the y's and plot the points
*May 4, 2015*

**Math**

A. for Carmen to run 3 times, Susan runs 4 times around the track for Carmen to run 1 times, Susan runs 4/3 around for Carmen to run 12 times, Susan runs 12(4/3) or 16 times around the track (notice that this is a straight ratio thing)
*May 4, 2015*

**Further mathemactics**

tan^2 Ø - sin^2 Ø = sin^4 Ø sec^2 Ø LS = sin^2 Ø/cos^2 Ø - sin^2 Ø = (sin^2 Ø - sin^2 Ø cos^2 Ø)/cos^2 Ø , using a common denominator. = (sin^2 Ø - sin^2 Ø(1 - sin^2 Ø)/cos^2 &...
*May 4, 2015*

**trig**

I assume you are solving this equation. btw, sec by itself is meaningless, since it is an operator, thus it needs an argument that's like saying 3 + √ = x anyway.... -2sec x = 3 sec x = -3/2 cosx = -2/3 the cosine is negative in quads II and III using my calculator ...
*May 4, 2015*

**math functions**

All three are correct #3 is correct assuming you are starting with n = 1
*May 4, 2015*

**Math**

Very simple LS = sin^2 x - cos^2 x = sin^2x - (1-sin^2 x) = 2sin^2 x - 1 = RS
*May 3, 2015*

**math**

Angles do not have area.
*May 3, 2015*

**trigonometry**

Did you not read my post? I told you how to do it.
*May 3, 2015*

**trigonometry**

let's just tackle the LS LS = sin(A+B)*sin(A-B) = (sinAcosB + cosAsinB)(sinAcosB - cosAsinB) = sin^2 Acos^2B - cos^2Asin^2B , the difference of squares pattern = (1 - cos^2A)(cos^2B) - cos^2A(1-cos^2B) = cos^2B - cos^2Acos^2b - cos^2A + cos^2Acos^2B = cos^2B - cos^2A = RS ...
*May 3, 2015*

**Math**

done look back when you posted it earlier
*May 2, 2015*

**trigonometry**

one rotation is 2π so -31π/6 ÷ 2π = -5 - π/6 so we have 5 clockwise rotations and another clockwise of π/6 (remember in trig, counterclockwise is positive and clockwise is negative) or consider the rotations in degrees 31π/6 radians = 930&...
*May 2, 2015*

**trigonometry**

Since arctan and tan are inverse operations, then logically arctan(tan(-31π/6)) = -31π/6 however .... since it probably wants the angle closest to the origin, and since tan(-31π/6) = tan(-π/6) arctan(tan(-31π/6) = arctan(tan(-π/6) = -π/6
*May 2, 2015*

**Math - Trigonometry**

Ls = 1/cosx - cos^2 x/cosx = (1-cos^2 x)/cox = sin^2 x/cosx = sinx sinx/cox = sinx tanx = RS How can you change 1/cosx - cosx to 1/cosx - cosx/cosx ?? you can't just toss in an extra cosx at the bottom that last term of cosx/cosx would reduce to 1
*May 2, 2015*

**Math - Trigonometry**

I have helped you with two of these now. I think it is time for you to try them. Hint: on the LS, find a common denominator and add the two terms Show me your steps and I will help you from there.
*May 2, 2015*

**Math - Trigonometry**

This one's really easy ... RS = sin^2 x - cos^2 x = sin^2 x - (1 - sin^2 x) = 2sin^2 x - 1 = LS
*May 2, 2015*

**Math - Trigonometry**

LS = 1/sinx + 1/cosx = (cosx + sinx)/(sinxcosx) = (cosx + sinx)(1/sinx)(1/cosx) = (cosx+ sinx)(cscx)(sec) = RS
*May 2, 2015*

**Calc 1**

Wasn't your tangent line supposed to pass through the origin?
*May 2, 2015*

**algebra**

well, let's just take the slope using the 2 given points slope = (y-2)/(3-1) = (y-2)/2 but we are told that the slope is 2 , so (y-2)/2 = 2 y-2 = 4 y = 6
*May 2, 2015*

**algebra**

what is (1/2)(1/2)(1/2) ?
*May 2, 2015*

**Math Calc**

You will need the vertex of this parabola I don't know what method you learned , so I will use the simplest way not using Calculus for y = ax^2 + bx + c, the x of the vertex is -b/(2a) so for yours, t = -112/-32 = 3.5 sub that back in to get the maximum height. when it ...
*May 1, 2015*

**math**

What is the question? Is this supposed to be an equation looking like 3x^2 - 27x^2 + 60x = 0 ?
*May 1, 2015*