Thursday
October 2, 2014

Posts by Steve


Total # Posts: 25,448

Plane and Spherical Trigonometry
Use the law of cosines. The third side can be found using AC^2 = 20^2 + 35^2 - 2(20)(35)cos(180-80)°
October 2, 2014

math
(g-48)(g-20) = 480 g = 60 So, the grandfather is 60. ...
October 2, 2014

Math
1/4 * 1/2 = 1/8
October 2, 2014

math
(14 - (15/3))/2 = 9/2
October 2, 2014

English - Parts of Speech
a simple google search will provide numerous examples.
October 2, 2014

maths
sorry, no diagrams here. But I bet you can do it. Just look in your text (or online) for similar situations, and change the numbers. You just have to draw two intersecting circles.
October 2, 2014

algebra
7 + 2x
October 2, 2014

Physics
A 0.60-kg basketball is dropped out of the window that is 6.1 m above the ground. The ball is caught by a person whose hands are 1.2 m above the ground. (a) How much work is done on the ball by its weight? (b) What is the gravitational potential energy of the basketball, ...
October 2, 2014

Physics
The drawing shows two boxes resting on frictionless ramps. One box is relatively light and sits on a steep ramp. The other box is heavier and rests on a ramp that is less steep. The boxes are released from rest at A and allowed to slide down the ramps. The two boxes have ...
October 2, 2014

Math
as with all fractions, multiply top and bottom by the GCD (a-1)(b) to get 1/(a-1) + 1/b = c b + (a-1) = c(a-1)(b) b + a - 1 = abc - bc a - abc = 1 - b - bc a = (1-b-bc)/(1-bc) = 1 + b/(bc-1)
October 1, 2014

Precalculus
If the width surrounding the rug is w, then (12-2w)(16-2w) = 12*16/2 Now just solve for w and determine the rug dimensions.
October 1, 2014

calculus
The curves intersect at (4,0) and (1,3). You don't specify the axis, so, assuming the x-axis, using shells, the volume is v = ∫[0,3] 2πrh dy where r = y and h = (5-(y-1)^2)-(4-y) v = 2π∫[0,3] 3y^2 - y^3 dy = 27π/2 Using washers, we have to break ...
October 1, 2014

Algebra HELP!
No ideas on any of them? Look for groupings of like expressions, difference of two squares, etc. For example, (g) is (x^2-y^2) + x + y (x-y)(x+y) + (x+y) (x-y+1)(x+y)
October 1, 2014

Algebra
Looks good to me. I tend to avoid fractions where possible, so I'd probably have done it as 42+48+x = 3*47
October 1, 2014

Math
(6+2w)(12+2w) = 520 w = 7
October 1, 2014

Math help!
(-2)^n+2n: -2+2, 4+4, -8+6, 16+8, ... n^2(-1)^n: -1, +4, -9, ... |10-n^2|: |10-1|, |10-4|, |10-9|, ...
October 1, 2014

Math
nope - that fixed fee of $32 wrecks the proportion.
October 1, 2014

Math
the length is clearly 36 cm The pieces can be (36/9)x26 or 36x(26/9) Assuming you want integer dimensions, I'd go with the first choice.
October 1, 2014

Math
68*3 + x = 70*4 you want large on top and small on bottom, so 984/12
October 1, 2014

Algebra
what, you have a problem evaluating expressions? (-2)^n+2n: -2+2, 4+4, -8+6, 16+8, ... n^2(-1)^n: -1, +4, -9, ... |10-n^2|: |10-1|, |10-4|, |10-9|, ...
October 1, 2014

algebra2/ trig
The centers of the pipes form an equilateral triangle, with sides of length 24. The belt then consists of three straight segments of length 24, and three arcs of the circles, subtending angles of 2pi/3.
October 1, 2014

algerbra 1
Strange language; I suspect you meany "by" 15, so on that basis, we have 2x = 3(x+4)+15 -x = 27 x = -27 and the numbers are -27 -25 -23 check: -54 = -69+15
October 1, 2014

Math
yes - just divide as shown 7/3 = 2.33 3/4 = 0.75 and so on
October 1, 2014

Math
#1 ok #2 - the discount was 15%, meaning the actual price was 85%, so 0.85p = p – 150 #3 WHAT? They just told you that A traveled 22 mph faster than B! If car B has speed s, then 2.4(s+22) = 4s This will give you B's speed. The distance traveled was 4s #4 If the ...
October 1, 2014

Math help!
clearly, at a change rate of -20 per year, (a) -20(5) = -100 (b) -20(-5) = +100 (c) -20n (d) -20(-n) = +20n
October 1, 2014

Trig
The first plane ends up at (169.7,-169.7) The other plane ends up at (-205.1,-205.1) So, relative to the first, the second plane is at (-374.8,-35.4) arctan(-35.4/-374.8) = 185.4°, or W5.4°S
October 1, 2014

Chemistry/Math
ppm of what? .01403g is just a mass. That's not much to go on
October 1, 2014

Algebra
just write each sentence in symbols, then solve the equations. #1 Maria has 105+10m Jana has 0 + 25m So, we want 105+10m = 0 + 25m Now just solve for m and then the amounts #2 There's a rental rate of r, and a late fee of f, so Nate: r + 1f = 5.50 Gina: r + 4f = 10.00 Now ...
October 1, 2014

Math-G7 Help please
#1 d = b+4 d+b = 22 #5 w(x+y) = 126 y = 2x #8 d+q = 20 10d+25q = 275 #15 s+a = 421 2s+5a = 1244 #17 b = s/3 b+2s = 84 Just translate each sentence into symbols.
October 1, 2014

Math
4(0) + 1(-3) + 1(-6) + 4x = 63 Now just solve for x
October 1, 2014

math
change in speed = 8 m/s at 2(m/s)/s, that will take 8/2 = 4 seconds
October 1, 2014

Algerbra math
(7+2)x^2 + (3+5)x + (9-2) That should help.
October 1, 2014

Math
any number bigger than the square root of Dalton's area.
October 1, 2014

math
to find y(x) for a specific x, just replace each x with its value. (a) y(-1) = -3(-1)-2 = 3-2 = 1 and so on (d) -a = -1(a) (e) just solve for x in -3x-2 = -11
October 1, 2014

College algebra
if there were x reserved seats, then the rest (40000-x) were general admission. So, adding up all the ticket prices, we get 12x + 5(40000-x) = 298000 x = 14000
October 1, 2014

Math- Multi-step word problems
3(s+20) = 3.20(s-20) s = 620 3*640 = 1920 3840/(3 + 3.20) = 619.35 so you are correct
October 1, 2014

Math- Multi-step word problems
d/(10-3) = d/(10+3)+1 so you are correct
October 1, 2014

Math- Multi-step word problems
If the plane's speed is s, then since distance = speed * time, 4(s+10) = 4.15(s-10) That gives s=543.33 553.33*4 = 2213 533.33*4.15 = 2213
October 1, 2014

Math--1 question
well, you can surely see that 56+c = 83 It's easy to find c, and it's not 33.
October 1, 2014

Trigonometry
Draw another line making an angle of 28°, passing through the tip of the overhang to the wall. If the height of sunlight on the wall is x, then (20-x)/6.11 = tan 28°
October 1, 2014

math
that depends on the tools you have at your disposal. Some curves have special properties, like the vertex of the parabola ax^2+bx+c is at x = -b/2a, and so forth. If you have access to calculus, you can find minima on a wider variety of curves. The most general tool would be a...
October 1, 2014

math
45(.80 - 1/3) = 21 The tank was not full at the beginning of the month, but only 80% full, or 36 gallons.
October 1, 2014

Maths
693 = 3^2 7 11 1365 = 3 5 7 13 The highest powers of all the primes in both lists are 3 7 so the GCF is 21
October 1, 2014

Math Multiplication
Just start trying divisors: 1 642 2 321 3 214 6 107 Since 642 = 2*3*107, that is all the factors there are
October 1, 2014

math
old diameter: d old area: pi/4 d^2 new diameter: 1.5d new area: pi/4(1.5d)^2 = pi/4 d^2 (2.25) So, new area - old area = 2.25-1 = 1.25 = 125%
October 1, 2014

math
hmmm. Looks like (54.28 - 48.70)/2 = 2.79 inches why the /2 ?
October 1, 2014

Trigonometry
as usual, amplitude = 1/2 period = 2π/π = 2 The - sign doesn't mean anything here, since cos(-x) = cos(x)
October 1, 2014

Trigonometry
C'mon. If 2π/k = .004, k = 2π/.004 = 500π
October 1, 2014

Trigonometry
this is just the other problem in reverse. Why not give it a shot? You know that the period of sin(kx) is 2π/k... Also, period = 1/frequency
October 1, 2014

Trigonometry
amplitude = 3 period = 2π/1 = 2π
October 1, 2014

math
Just looking at the formula, you could surely see that 10 is wrong, because then the area would be 100π = 314, not 658. So, πr^2 = 658 r^2 = 658/π = 209.4479 r = 14.47
October 1, 2014

physics
If the boat's speed is s, and the river's speed is r, and the boat is traveling east (0 degrees), (0,r) + (s cos297,s sin297) = (6,0) now just solve for r and s.
October 1, 2014

math
(6x^3+13x^2+6x+158)/(3x+11) = 2x^2-3x+13 R 15 If that was supposed to come out even, I suspect a typo. I guess you will have to figure out why NCC is important.
October 1, 2014

Pre-Calculus/Trig...
Surely you can graph both those simple functions. Just switch from one to the other at x=1. since 0 < 1, f(0) x^2 = 0.
October 1, 2014

College Alg
P(x) = R(x)-C(x), so just solve for x in x(50-.002x) - (12x+150000) = 1650000 I suspect a typo, since that has no real solutions.
October 1, 2014

slopes
actually, you mean the line joining the two points. well, starting at (4,9), how much do x and y change getting to (2,9)? y does not change, so the slope is zero.
October 1, 2014

Basic programming principles
incorrect
October 1, 2014

Basic programming principles
First, let's add some parentheses to indicate order of operation: ((A * 3 >= B – 14 \ 3)AND(F)) OR (C <= D+3) Now, anything AND FALSE is FALSE, so we are left with FALSE OR (12 <= -4+3) FALSE OR FALSE FALSE
October 1, 2014

Basic programming principles
well, is 4+20 <> (4+17)*4 ? Looks true to me.
October 1, 2014

chaitanya
measuring from the first point, s(t) = vt + 1/2 at^2 we know that s(6) = 180, so 6v + 18a = 180 Also, we have v + 6a = 45 So, v=15 and a = 5
October 1, 2014

physics
The boat and its contents are floating, so its general density is less than that of water. So, the boat displaces a volume of water which has the same mass as the boat. But a rock is denser, so it displaces less water. SO, the amount of water displaced drops when the rock ...
October 1, 2014

math
d and e are obviously out, since they do not start with 3. Of the others, which has terms that increase by 2?
October 1, 2014

Math
(3*7 + 9*8)/(8*7)
October 1, 2014

math
350P3 = 350*349*348
October 1, 2014

Math
why don't you give it a shot? Just start listing them, but don't list any letter twice.
October 1, 2014

Math
-2(-2)+10 is not 8 use the slope-intercept form: y-8 = -2(x+2) y = -2x + 12
October 1, 2014

Find the pattern
If you start with #8, you can pin down certain days. Surely you can make some headway in this.
October 1, 2014

Pre-caluclus
well, I don't know what "7500 1" means, but I'll just call it 7500 and you can fix it as needed. For the inverse, swap variables and solve for y: t = 7500 + 749e^(-0.15y) t-7500 = 749e^(-0.15y) e^(-0.15y) = (t-7500)/749 -0.15y = log[(t-7500)/749] y = -log[(t-...
September 30, 2014

Math
1 in = 2.54 cm, so you have (2*36 + 2*12 + 5)(2.54) = 256.54 cm Do the other the same way. Next time you get a wrong answer, show your work, and we can fix what's wrong.
September 30, 2014

Math
wow, didn't get far, eh? Just start solving for y: x = (1+2y)/(1+y) x(1+y) = 1+2y x + xy = 1 + 2y x-1 = 2y - xy x-1 = y(2-x) (x-1)/(2-x) = y Easy, no? The domain of f(x) is all real numbers except where the denominator is zero. That is all values except -1. The domain of ...
September 30, 2014

Math
But, just to get you started, if there are $x at 6%, the rest (1000-x) is at 9%. So, add up the interests earned: .06x + .09(10000-x) = 750.00 Now just crank it out.
September 30, 2014

Geometry
the hypothesis comes after "if". so your first answer is correct.
September 30, 2014

Math
13 and 15 occur most frequently. The center value is 15. Depending on how many other numbers there are, just start putting them on both sides of 15 (the median), making sure they always add up to 15*n, where there are n numbers. And make sure that 13 and 15 occur the most.
September 30, 2014

Math z-scores
you can play around with Z stuff at http://davidmlane.com/hyperstat/z_table.html It shouldn't take long to answer your question
September 30, 2014

algebra 2
(ab)^2 - 2^2
September 30, 2014

Precalculus
P(x) = (x-4)(x+5)^2 now it's easy, right?
September 30, 2014

Algebra 1
#1, Clearly not true for x=10 Try C if it's supposed to read 4x^2 <= (4x)^2 because (4x)^2 = 16x^2 #2 A, just as in #1. (5x)^2 = 25x^2 >= 5x^2 take a look at wolframalpha.com, where you can plot several functions on the same axes. For example, http://www.wolframalpha...
September 30, 2014

Trigonometry
The length of the ladder does not matter. We are told that cos x = 1/4 x = 75.52°
September 30, 2014

Math
4(2x + 3) = 2(3x - 4) 8x+12 = 6x-8 2x = -20 x = -10 Bzzzt 6 - a = 1/3(9a - 18) 18-3a = 9a-18 12a = 36 a = 3 correct 3(4x - 3) - 7x = 5x - 9 12x-9-7x = 5x-9 5x-9 = 5x-9 correct - the same line 4(2x - 3) - 4x 8x-12-4x 4x-12 2(2x-6) 4(x-3) only your first choice is correct
September 30, 2014

Trigonometry
You have to know the size of the court. Assuming the spike is driven parallel to the side lines, then if the distance to the far line is x, and assuming you want the angle from the vertical (otherwise you'd be asking for the minimum angle), then x/2.44 = tan θ See how...
September 30, 2014

MATH HELP PLEASE
(5.1 × 10^3) • (3.2 × 10^3) (5.2×3.2)×(10^3×10^3) 16.32×10^6 But that is not scientific notation. The leading number must be at least 1.0, and less than 10, so you need to shift the decimal point and adjust the exponent: 1.632×10^...
September 30, 2014

Trigonometry
surely you know that cos(180°) = -1 so, arccos(-1) = 180°
September 30, 2014

Pre-Calculus/Trigonometry
you could eliminate the x by doing some judicious multiplying: 24x-6y = 15 -24x+6y = 14 Now add the equations to get 0y = 29 BZZZT! No solution
September 30, 2014

math
got me. What is R?
September 30, 2014

College Algebra
since time = speed * distance, then if her outbound speed was x, then 12/x + 12/(x-10) = 1 x = 30 or 4 Check: 12/30 + 12/20 = (24+36)/60 = 1 The other solution to the equation is x=4. Why is that not useful?
September 30, 2014

Math
#1 EVERY function has a domain. A function is a relation between two sets: the domain and the range. The domain of any polynomial function is all real numbers. #2 If you mean f(x) = 1/(x+5), then you are correct (except you meant x ≠ -5) #3 correct If you meant √(x+2)
September 30, 2014

Math
as with any vector of length r on an angle of t, x = r cos(t) y = r sin(t) So, plug in your numbers.
September 30, 2014

math
98 - (-94) = 98+94 = ?
September 29, 2014

Precalculus
use the vertical and horizontal line tests. If no line cuts the graph in more than one place, the function is 1-1 and has an inverse. That is, each x value maps to exactly one y value, and vice-versa.
September 29, 2014

horizon elementry
v = at, so 8 = a(.5) a = 16 m/s^2
September 29, 2014

precal
ok. now what?
September 29, 2014

Precalculus
Look at the bottom row of the table, dude!
September 29, 2014

Material Behavior
I don't know what F is, but dU/dr = Am/r^(m+1) - Bn/r^(n+1) So, plug in r0 and you have dU/dr(r0) = Am/r0^(m+1) - Bn/r0^(n+1)
September 29, 2014

Math
almost. 3/7 = .4286 so -3 3/7 is 2nd in the list
September 29, 2014

Algebra
it means it is ill posed. The math is correct, but the problem doesn't take into account real-world conditions. Just ignore it, as this is an algebra class, not a physics class. Still, you might point it out to the teacher, not that it will do any good.
September 29, 2014

Algebra
well, clearly the temperature is now -247 - 2*11 = -269 The only problem is that hydrogen freezes at -259
September 29, 2014

Math
36+81 = 9(4+9) or 3(12+27)
September 29, 2014

Geometry
If the numbers are m and n, and m is even, then m=2k. If the sum is even, say 2x, then 2k+n = 2x n = 2x-2k = 2(x-k) So, it is clear that n is also even, since it is a multiple of 2.
September 29, 2014

math
2*16 + 2*3 = 38 or, 2(16+5)-4 = 38 why the two ways of writing the expression?
September 29, 2014

Math
recall that (a+b)(a-b) = a^2-b^2 so, (3+√5)(3-√5) = 9-5 = 4 So, to simplify such fractions, look for the "square conjugate" if you will, of the denominator. 4/(3+√5) = 4(3-√5) / (3+√5)(3-√5) = 4(3-√5)/4 = 3-√5 And do ...
September 29, 2014

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