Saturday

December 20, 2014

December 20, 2014

Total # Posts: 27,642

**Algebra 1**

Yes I can. Thank you from a 68 year old Grandfather helping his Grandson
*December 13, 2014*

**Algebra 1**

What does the graph of y = absolute X-2 look like?
*December 13, 2014*

**Algebra 1**

Thank you -- A Grandfather trying to help his Grandson.
*December 13, 2014*

**Algebra 1**

Describe how the graphs of y = absolute value of x,and y = absolute value of X -15 are related. 1- Them graphs have the same shape. The y intercept of y = absolute x is 0, and them x intercept of the 2nd graph is -15. 2-m The graphs have the same y intercept. The second graph ...
*December 13, 2014*

**math**

Assuming the robot is completely submerged, then the water will rise by (20m^3)/(5m*4m) = 1m Doesn't really matter how tall the tank is, or how much water is already there, as long as the entire volume of the robot is submerged.
*December 13, 2014*

**math**

(-5/10)(-5/4) (-17/13)(-65/136)
*December 13, 2014*

**algebra**

A = Pe^(rt)
*December 13, 2014*

**algebra (please help)**

If $x is at 4.25%, the rest (22000-x) is at 5.75% So, just add up the interest received: .0425x + .0575(22000-x) = 1085
*December 13, 2014*

**algebra (please help)**

you are told that 2c+f = 1120 3c+2f = 1870 Now just solve for c and f.
*December 13, 2014*

**algebra**

the cost for x items is 4000+2.19x the income for x items is 4.59x Breakeven is where income and cost are equal: 4.59x = 4000 + 2.19x For 5500 profit, you need 4.59x = 4000 + 2.19x + 5500
*December 13, 2014*

**math**

πr^2h = 512 So, h = 512/(πr^2) area a = 2πr^2 + 2πrh = 2πr^2 + 2πr (512)/(πr^2) = 2πr^2 + 1024/r Assuming you have calculus, we see that da/dr = 4πr - 1024/r^2 da/dr=0 when r = 4∛(4/π) Now you can find h.
*December 13, 2014*

**Math**

f(x) = sin(x) df = cos(x) dx So, since sin(30°) = 1/2 sin 27° = 1/2 + (√3/2)(-π/60)
*December 12, 2014*

**Algebra**

can't be both. For floor, round down to next integer for ceiling, round up to next integer
*December 12, 2014*

**Algebra**

1 sometimes 0^0 is undefined 2 never 3 never 4 sometimes .3^1 < 1
*December 12, 2014*

**Algebra**

well, just solve 46 + .024x = 1558
*December 12, 2014*

**Math**

5r(13r+3s-5s^2) = 65r^2+15rs-25rs^2 -6s(13r+3s-5s^2) = -78rs-18s^2+30s^3 s^2(13r+3s-5s^2) = 13rs^2+3s^3-5s^4 Add them up to get 65r^2 - 63rs - 12rs^2 - 18s^2 + 33s^3 - 5s^4
*December 12, 2014*

**geometry**

google the number of segments determined by n points is and you will find many discussions of the topic. Find the one you like and use n=4.
*December 12, 2014*

**Grade 9 Science**

the orbit is not a circle, but an ellipse. The planet is not always exactly the same distance from the sun. Read up on Kepler's laws of planetary motion.
*December 12, 2014*

**physics 1**

This is just the same as figuring the time it takes for an object to fall 2cm on earth, except that the gravitation acceleration is not 9.81 m/s^2, but GM/r^2 where you have the values for G,M and r. Once you have that evaluated, s = 1/2 at^2 and you can just plug in s=0.02m ...
*December 12, 2014*

**Calculus - Correction**

Oops. The part from 0 to 0.0667 is not included, because it's all inside r=1. So, the real area is just 2∫[0.0667,π/2] 1/2 ((15sinθ)^2-1^2) dθ
*December 12, 2014*

**Calculus**

The area inside a polar curve is ∫1/2 r^2 dθ The circles intersect where 15sinθ = 1 θ = 0.0667 So, from 0 to 0.0667, we have r = 15sinθ From 0.0667 to π/2, we have to subtract the area inside r=1 from r=15sinθ, so the area is twice the area ...
*December 12, 2014*

**calculus (check)**

f(x) looks good No idea what F(n) is. If you mean the sequence of partial sums, it's just the normal sum formula for A.P.'s.
*December 12, 2014*

**calculus (Series)**

You just want the sum of the series where a = -2.02 d = -0.09 n = (-4 +2.02)/-.09 = 22 S22 = 22/2(-2.02 + -4) = -66.22
*December 12, 2014*

**Calculus**

You just want the sum of an arithmetic series where a = 4 d = 1/2 S28 = 28/2(2*4 + 27(1/2)) = 301
*December 12, 2014*

**Math**

That's what I get
*December 12, 2014*

**Physics**

Assume the heavier satellite is traveling in the +x direction. Conserve momentum, so the final velocity (xi+yj) is the solution to 1000*500i + 400*700(.707i+.707j) = (1000+700)(xi+yj) That will give the x- and y-components of the final velocity, which you can then express as ...
*December 12, 2014*

**math**

(n-2)180 / 360 = 4 So, find n to determine the number of sides, and that will let you find the angles.
*December 12, 2014*

**algebra**

I'd guess from previous posts that we want y > -5/3 x + 3 But what we are to do with it I don't know.
*December 12, 2014*

**algebra 2**

2√3+√27-√1/3 2√3+3√3-1/√3 5√3 - 1/√3 (5*3-1)/√3 14/√3 √1/2•(√8+√2) 1/√2 * 2√2 + 1/√2 * √2 2 + 1 3 √18-√3/√6 3√2 - √3/(√3√2) 3&#...
*December 12, 2014*

**physics**

BCE potential and kinetic energy depend on mass.
*December 12, 2014*

**Geometry**

tanθ = 1.89/50
*December 12, 2014*

**Sequences**

a10 = 6 + 9*8
*December 12, 2014*

**Math**

(13.69 + 3.96)/6
*December 12, 2014*

**Math - Sooyong**

vertical lines have no y-intercept horizontal lines have no x-intercept (unless these lines are in fact x=0 or y=0) #2 ok #3 also yes. Pick any point on the line (and there are an infinite number of points) and you can draw a perpendicular line through it.
*December 11, 2014*

**Math**

the minimum cable length occurs where f'(x) = 0 So, you need 2x/√(x^2+16) - 1 = 0 2x - √(x^2+16) = 0 2x = √(x^2+16) 4x^2 = x^2+16 3x^2 = 16 x = 4/√3 So, the minimum cable length is f(4/√3) = 10+4√3
*December 11, 2014*

**Math**

As usual, draw a diagram, and it is clear that f(x) = (10-x) + 2√(x^2+16) f'(x) = -1 + 2x/√(x^2+16) f"(x) = 32/(x^2+16)^3/2 Now the answers are easy to provide
*December 11, 2014*

**algebra**

When the car starts, the truck is 56/4 = 14 miles ahead. the car is going 8 mi/hr faster. So, how long will it take to make up the 14 miles? Add that to the 1/4 hr the truck already traveled.
*December 11, 2014*

**Physics**

300rev/min / (1/120 min) = 36000 rev/min^2 Now you can convert that to whatever units you like. Remember: 2pi radians/rev
*December 11, 2014*

**math**

2(w + 2w) = 72
*December 11, 2014*

**math**

xy=20 x+y = x + 20/x minimum occurs where x=2√5 (same as the problem for finding maximum area for a given perimeter: a square) So, pick two integers near √20. They would be 4 and 5, with sum=9 The only other sums are 1+20=21 2+10=12
*December 11, 2014*

**Pre-Calc**

Note that if you multiply on the left inside the radical, by (1-sinx)/(1-sinx), you have √((1-sinx)^2/(1-sin^2(x)) That should get you most of the way there, since √x^2 = |x|
*December 11, 2014*

**trig**

well, the perimeter is the sum of the sides, so 3n-4 + 3n+9 + 4n+5 = 114 10n = 104 Now it's easy to find n, and then figure the actual side lengths.
*December 11, 2014*

**statistics finding the shaded region**

enter your data here. http://davidmlane.com/hyperstat/z_table.html It's a great Z table site.
*December 11, 2014*

**Algebra 2**

well, note that f(x) = 5(x^3-2^3) = 5(x-2)(x^2+2x+4) That help?
*December 11, 2014*

**statistics probability**

P(-1.39<=Z<=1.69) = 0.8722 You can play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html
*December 11, 2014*

**Math**

If the mother's age is x, x/2 - 10 = 12 x = 44
*December 11, 2014*

**maths**

log_2(a) = 2log_4(a) = 3log_8(a) So, you have 2/(1/3 log_2(a)) - 4/log_2(a) = 1/(1/2 log_2(a)) 1/log_2(a) (6 - 4) = 2/log_2(a) 6-4 = 2 Or, recall that log_b(a) = 1/log_a(b) So, you have 2log_a(8) - 4log_a(2) = log_a(4) But, since 8=2^3 and 4=2^2, that means 6log_a(2) - 4log_a(...
*December 11, 2014*

**algebra**

log_8(2)+log_8(4x^2) = 1 1/3 + log_8(4) + log_8(x^2) = 1 1/3 + 2/3 + log_8(x^2) = 1 log_8(x^2) = 0 x^2 = 1 x = ±1 ln2 - ln(3x+2) = 1 ln (2/(3x+2)) = 1 2/(3x+2) = e 2/e = 3x+2 x = (2/e - 2)/3 = 2(1-e) / 3e ln(x-3) - ln(x-5) = ln 5 (x-3)/(x-5) = 5 x-3 = 5x-25 x = 11/2
*December 11, 2014*

**algebra**

well, clearly the spacing indicates -e^(-3.9n-1) -1 = -3 e^(-3.9n-1) = 2 -3.9n-1 = ln2 n = -(1+ln2)/3.9 Of course, I could be way off...
*December 11, 2014*

**Math**

since 36=6^2 its exponents are only half as big as powers of 6 to get to the same value. That is, log_36(n) = 1/2 log_6(n) So, 1/log_36(a) = 1/ (1/2 log_6(a)) = 2/log_6(a)
*December 11, 2014*

**Algebra 2**

remember the difference of cubes, and you see that you have (2x)^3 - (10y^2)^3 (2x-10y)((2x)^2+(2x)(10y^2)+(10y^2)^2) = 2(x-5y)(4x^2+20xy^2+100y^4) = 8(x-5y)(x^2+5xy^2+25y^2)
*December 11, 2014*

**Middle School Math**

Not at all. 3g+5 = 17 3g+5-5 = 17-5 3g = 12 3g/3 = 12/3 g = 4 I'd be interested to see how you arrived at -20.
*December 11, 2014*

**math**

If the ratio is 2:3, then games won = 2/5 of 120 = 48 So, games lost is 3/5 of 120 = 72 The correct proportion would be x/120 = 3/5 Consider. If the ratio is 2:3, the won/lost = 2/3 won = 2/3 lost lost+won=120 lost + 2/3 lost = 120 5/3 lost = 120 lost = 120 * 3/5 = 72
*December 11, 2014*

**math show work please**

You just need 2^(t/7) = 3 (t/7) log2 = log3 t = 7log3/log2 = 11.1 hours
*December 11, 2014*

**algebra**

that would be the cost per ride, since the only thing that changes is the number of rides.
*December 11, 2014*

**Math**

You are correct. 4 was indeed the solution to the equation, but you correctly went on to realize that that meant the actual price was $8/mug. Good work. Still, just plugging x=4 into the equation would have given the same answer for the income, since that accounted for the ...
*December 11, 2014*

**Math**

It would surely help if you showed how you got there. What you provide is not much help. If x is the number of price increases, then we have price p = 6.00 + 0.50x quantity sold q = 200 - 10x revenue is price * quantity, so r(x) = (6.00 + 0.50x)(200-10x) = 1200+40x-5x^2 This ...
*December 11, 2014*

**Math**

no, the amplitude is the coefficient out front: 37 You know the amplitude of sin(x) is 1 5 in this case isn't really anything. It might look like a phase shift, but it's not even that. And you still have a typo, since there's no t anywhere on the right side. You ...
*December 11, 2014*

**Trig**

so, since when is 1/2 pi not the same as pi/2?
*December 11, 2014*

**Math**

diameter is 35, so radius is 17.5 -- that is the amplitude of f(t) f(t) is like 17.5 sin(t) Since the max height is 50, that means the axle is at 50-17.5 = 32.5 f(t) is like 17.5 sin(t) + 32.5 The period of sin(kt) is 2pi/k, so we need 2pi/k = 13 k = 2pi/13 f(t) = 17.5 sin(2pi...
*December 11, 2014*

**Algebra**

well, just plug in the numbers and see whether it's true. 5(-2) - 2(-1) + 1 > 0 -10 + 2 + 1 > 0 -7 > 0
*December 11, 2014*

**Math**

since the range of sin(x) is [-1,1] that is the domain of sin^-1(x).
*December 11, 2014*

**Math**

In no way! 3/12 = 25% 50% is 6/12 !
*December 10, 2014*

**Math**

there were 12 plants in all 3 had no fertilizer. 3/12 had no fertilizer. Is C your final answer? ...
*December 10, 2014*

**trigonometry**

A. 4.5/x = tan 25° B. 4.5/x = sin 25°
*December 10, 2014*

**math**

121 = 7+2x
*December 10, 2014*

**Math 6th grade**

3 1/4 = 15/4 pizzas each person got 1/4 * 15/4 = 15/16 of a pizza Joe ate 1/4 of his portion, so he ate 1/4 * 15/16 = 15/64 of a pizza Extra credit: who stole the other 3/4 of a pizza? No one buys 3 1/4 pizzas!!
*December 10, 2014*

**Math**

Actually, since -(-(-x)) = -x we have |-x| = -x which is true for all x <= 0 Still the correct answer, though.
*December 10, 2014*

**Math solve the equation**

7x = 72 7x/7 = 72/7 x = 72/7 9p = 30 p = 30/9 or 10/3
*December 10, 2014*

**German**

yes, but it is incorrect. das Kind ein Kind no "eine" allowed. And, since Kind is a noun, it is always capitalized. Now, with adjectives, following a definite article, they are all ending in e. Otherwise, they are inflected by gender: das kleine Kind ein kleines Kind...
*December 10, 2014*

**Algebra2**

I'd be interested in seeing your work. I get (h-6)/150 = tan 46.2° (h-6)/150 = 1.04 h-6 = 156.42 h = 162.42
*December 10, 2014*

**Algebra2**

If the height is h, then (h-6)/150 = tan 46.2°
*December 10, 2014*

**pre-algebra**

5n >= 300*1.25 + 500 5n >= 375+500 n >= 175
*December 10, 2014*

**Calculus**

y = e^-x^2 y" = (4x^2-2)e^-x^2 y"=0 when x = ±√2 y(±√2) = e^-2 = 1/e^2 = 1/e^a Looks like a=2
*December 10, 2014*

**math**

The first train travels 16(6 37/60) = 96 592/60 = 105 13/15 min = 105'52" or 1 hr 45 min 52 sec do the other similarly
*December 10, 2014*

**Math**

y' = 7x^3+28x^2-63x-252 = 7(x+4)(x+3)(x-3) Now things should be easy. You know y is increasing when y' > 0...
*December 10, 2014*

**Algebra**

even-root radicals have domain only positive reals, since even powers of all numbers are positive odd powers can be negative or positive, so odd-root radicals have domain all reals.
*December 10, 2014*

**Math**

80/x + 80/(x+10) (80(x+10)+80x) / x(x+10) (160x+800) / x(x+10)
*December 10, 2014*

**Pre-Calc/Trig...**

by definition, ln(e^x) = x e^(lnx) = x ln and e^ are inverse operations. Just as cos(arccos(x)) = x √(x^2) = x a*(x/a) = x a+(x-a) = x So, ln e^4.3 = 4.3 e^(ln 4.3) = 4.3
*December 10, 2014*

**Math**

hint: -9x^2-55x+56 = (7+x)(8-9x)
*December 10, 2014*

**Math**

you are correct
*December 10, 2014*

**math**

h√-1
*December 10, 2014*

**Math**

5.815 < 6.021
*December 10, 2014*

**calculus**

s(t)=250-3t+9t^2+2t^3 v(t) = -3+18t+6t^2 a(t) = 18+12t plug in t=0 for initial values. the other questions are just normal ideas. What do you get?
*December 9, 2014*

**Math**

factors: 1,2,3,6,7,14,21,42 So, which add to -19? 2-21
*December 9, 2014*

**help asap**

well, find the slopes of AC and BD. If their product is -1, they are perpendicular.
*December 9, 2014*

**math**

17(2+3) = 17(5) = ?
*December 9, 2014*

**AP Calc**

a = pi d^2 when a=3, d^2 = 3/pi v = pi/6 d^3 dv/dt = pi/2 d^2 dd/dt So, -pi/18 = pi/2 (3/pi) dd/dt dd/dt = -pi/27 in/min
*December 9, 2014*

**Calculus- Tangent Line**

looks good to me. Of course, it would help to know just what the curve was ...
*December 9, 2014*

**Math**

x^2+4x = x(x+3) 2x^2+13x+15 = (2x+3)(x+5) x^2-16 = (x-4)(x+4) So, what you have is x(x+4)(x+5) ------------------ (2x+3)(x+5)(x+4)(x-4) That leaves you with x / (2x+3)(x-4)
*December 9, 2014*

**Math**

72x^7
*December 9, 2014*

**Statistics**

10P4 = 10*9*8*7
*December 9, 2014*

**fuctions and statistics**

you can always multiply by 1 without changing anything. You know that 1 ft = 0.3048 m That means that 1ft/0.3048m = 1 0.3048m/1ft = 1 Now, you want to convert feet to meters, so just multiply by the "correct" representation of 1, so that the units cancel out as you ...
*December 9, 2014*

**English**

They look ok to me. And yes, "according to" is ok, as well. I guess you are all "set" now, eh?
*December 9, 2014*

**English**

#2 is correct, except for the typo. I'd never use "the" in this case. However, it is correct to say He must have been late for the bus. A bus is a specific vehicle, but "school" is a more vague entity, implying education and other activities, and not ...
*December 9, 2014*

**Physical Science**

All oxygen boils at -183 C, but I have no idea what temperature your oxygen is at.
*December 9, 2014*

**math(5th grade)**

zero, if the school is north of his home.
*December 9, 2014*

**Calculus**

well, you remember that inflection is where y" = 0 concave up when y" > 0 For y" I get 2 times your answer, but that doesn't change its properties. y' = 2cosx(sinx+1) y" = -sinx + cos^2x - sin^2x = -sinx + 1 - 2sin^2x = -(2sinx-1)(sinx+1) Note ...
*December 9, 2014*

**Calculus**

the line has slope 2/3 So, the normal needs slope -3/2 3x^2-4y^2=8 6x - 8yy' = 0 y' = 3x/4y So, we need 3x/4y = -3/2 y = -x/2 3x^2-4(-x/2)^2 = 8 3x^2-x^2 = 8 x = ±2 y = ∓1 So, we want lines through (2,-1) and (-2,1) with slope -3/2 y-1 = -3/2 (x+2) y+1 = -...
*December 9, 2014*

**Calculus**

I suspect a typo. Why the ^1 ? At x=0, you have (1+0)^1/0 = 1/0 = +∞
*December 9, 2014*

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