# Posts by steve

Total # Posts: 52,268

**Math**

median=10, 6 numbers, so median is between 3rd and 4th .. 9 11 . . mode=11 .. 9 11 11 . range=4 7 8 9 11 11 11

**math**

(x+y)^2 + (x-y)^2 = x^2+2xy+y^2 + x^2-2xy+y^2 = 2(x^2+y^2) ...

**Math**

apparently white is + and black is - big black square: -x^3 small black square: -x rectangles: x^2 or 1 See what you can do with that...

**math**

xa-xb = x(a-b) = 12 a-b = 2*3 = 6 x = x(a-b)/(a-b) = 12/6 = 2

**math**

a/x = (b/x)(a/b) so, 36/x = 36*6 1/x = 6

**math**

your copy/paste mangled the 2nd expression, but if it is (a-b)^2 = 64, then (a+b)^2 + (a-b)^2 = a^2+2ab+b^2 + a^2-2ab+b^2 = 2(a^2+b^2) so, 2(a^2+b^2) = 100+64 a^2+b^2 = 82

**math**

x^2-y^2 = (x-y)(x+y) = ab

**maths**

if you don't like the law of sines, just study the tan/cot functions. You can easily see that the height h can be found from h cot25° - h cot37° = 57

**Calculus**

the line from (1,1) to (3,2) is just y-1 = 1/2 (x-1) y = 1/2 x + 1/2

**math-limit**

some parentheses would also help. Since (?5 + x - ?5)/x = 1, that's probably not what you had in mind. (?(5+x)-?5)/x -> 0/0 so, multiply top and bottom by (?(5+x)+?5) and you end up with ((5+x)-5)/(x(?(5+x)+?5)) see where that takes you...

**math**

sorry - still not much use...

**math**

solve for r in (1+r)^15 = 426/258

**math**

the "mid" or "bi" or "med" indicates the middle, so ...

**Science(maths)**

(# moles)*(H atoms per molecule)*6.023*10^23

**science**

when: 100-4.9t^2 = 25t-4.9t^2 where: evaluate either expression at the found value of t.

**math**

25cm/3m = 25cm/300cm = 25/300 = ?

**Science**

almost, but no.

**Mathematics**

nope. It's just that the series converges iff |t| < 1 If you look at the formula, it's the same whether t<1 or t>1. The signs of the numerator and denominator both change, but the result is the same.

**Mathematics**

If t = (5x+6)/(3x-2) then |t| < 1 if -4 < x < -1/2

**Pre-Calculus 12**

well, you have to know the basic steps to finding intercepts and asymptotes. Review the examples in your text, and then it's just a matter of figuring out the relevant features of the graph. The intercepts and stuff are just handy landmarks to pinpoint specific places.

**Pre-Calculus 12**

y = (x-5)(x+2)/(x-2) a fraction is zero when its numerator is zero, right? Damon was just trying to give you the x-intercepts as an aid to graphing the curve. With Damon's input, you have the x-intercepts, the asymptote, and the y-intercept. Unfortunately, the asymptote is...

**math**

is that 1/z + 3 or 1/(z+3) ? Take a look at https://math.stackexchange.com/questions/1792628/complex-variable-limit-at-infinity

**Physics**

see your previous post

**math**

convert all dimensions to yards, and you have v = 6/3 * 160/3 * 1/4 = 80/3 yd^3

**Physics**

Ah. I see I forgot to include the initial height of 2 meters. I assume you discovered that, and made the required adjustment to the equation.

**Physics**

recall that the ball follows the path y = tan? x - g/(2 (vcos?)^2) x^2 plugging in your numbers, then, we need to solve tan39° * 8 - 4.9/(v cos39°)^2 * 64 = 3.04 6.478 - 519.243/v^2 = 3.05 v = 12.307 m/s

**Physics**

Hmmm. I also get 4.36 We forgot the ball's initial downward velocity of 5sin15° = -1.294 m/s. Unfortunately, that makes it worse, since it falls faster. Now we have to find t such that -1.294t - 4.9t^2 = -4 t = 0.781 and that means the ball only goes 5cos15° * 0....

**Physics**

just realize that when the ball leaves the ramp, its horizontal speed remains constant at 5cos15° How long does it take to fall 4 meters? 4.9t^2 = 4 use that time to see how far the ball travels horizontally.

**Math**

cos2x+sinx = 0 1 - 2sin^2x + sinx = 0 (2sinx+1)(sinx-1) = 0 sinx = -1/2 in QIII,IV sinx = 1 I expect you can take it from there.

**Math**

just remember to use the product rule. Also, dx/dx = 1 x^2y^2-3xy+4xy^3=5 2xy^2+2x^2yy' - 3y-3xy' + 4y^3+12xy^2y' = 0 y'(2x^2y-3x+12xy^2) = -2xy^2+3y-4y^3 y' = -2xy^2+3y-4y^3 --------------------- 2x^2y-3x+12xy^2

**math**

yes.

**Math-ASAP please**

ok ok I see that you are unwilling to confirm what you can online. The simple polynomial divisions can indeed be done at either site. #1 is wrong #2 area is length*width so, length = area/width x^3 - 7x + 6 = (x-6)(x-1) try again. #3 makes no sense to me. How did you arrive at...

**Math-ASAP please**

you can confirm your answers by typing in your expressions at wolframalpha.com be sure to use enough parentheses so that it interprets your input correctly. Or, you can see all the details of the divisions at http://calc101.com/webMathematica/long-divide.jsp

**Algebra 1 B Unit 6: Rational Expressions and Func**

well, (-18x^3+17x+6) = -(3x+2)(6x^2-4x-3) so, what do you think?

**algebra 1**

Think about it, and you will see that your answer is way off. At the very least, the fact that the question is asking about permutations should tip you off. There are 8 ways to pick the first position. For each of those 8 choices, there are 7 ways to pick the next one. ...

**Math**

at any rate, 60 = 12*5, so it will take 12 time-units.

**math**

surely you must have some ideas on these. It's not rocket surgery, ya know ...

**Math**

they travel for 1.5 hours, at a combined rate of 120 mi/hr, so ...

**math**

5000*(1+.085)^4*(1+.0925)^3

**math**

the area scales by the square of the linear factor. So, 160 is 4 times the model's area.

**Algebra 2**

May is the 5th month. So, f(4)=4.5sin(4?/6)+11.8 = 4.6*?3/2 + 11.8 = 15.784 and it must be a strange location, since the minimum temperature occurs in October . . .

**@oops on (iii)**

sorry. I figured the distance in meters, not the velocity in m/s. See whether you can fix my mistake.

**physic, please correct is am wrong**

(i) one revolution is 2?radians, so ? = 200*2? = 400? radians (ii)angular velocity is measured in radians/second, so ? = ?/t = 400?rad/24s = 50?/3 rad/s (iii)v = r?t v = 1/4 * 50?/3 * 24 = 100? m/s or, since the circumference is ?d = ?/2 meters per revolution, v = 200rev/s...

**math 11**

A = x(50-x)

**physic**

any information on the directions?

**math**

If you mean 2 2/5 - 1 5/9 then that would go 12/5 - 14/9 and using an LCD of 45, 108/45 - 70/45 38/45

**maths**

if you draw a side view, you can easily see that the slant height s is 13. So, the area is a = ?r^2 + ?rs

**science**

google is your friend, as in http://www.topperlearning.com/forums/home-work-help-19/can-a-sphere-of-radius-1cm-hold-a-charge-of-1-coulomb-physics-electric-charges-and-fields-67613/reply

**Pre-Calculus**

sin ?/6 = 1/2, so that is your reference angle In QIII, x = ?+?/6 = 7?/6 so, 2x = 7?/3 = 2?+?/3, in QI So, tan2x = ?3

**Maths**

since corresponding angles are congruent, we have 3y+30 = 10y-40 4x-100 = 3x-30 Now just crank it out.

**Math**

depends on which angle is at the vertex. If Y is at the top, then 2y+y+2y = 180 Otherwise, y+2y+y = 180

**math**

you should recognize a scaled-up 3-4-5 right triangle. So, the diagonal is 100 ft. The rest is a cinch, right?

**maths**

I will assume that A and ? are the same Draw a triangle. The legs are a and b, so the hypotenuse is ?(a^2+b^2) Now you know that sec? = 1/cos? = ?(a^2+b^2)/b I expect you can handle the rest of the algebra...

**Math**

you need a denominator which is the least common multiple of the given denominators. For example, if you have 2/3 and 3/5, the LCD is 3*5 So, these work the same way. #1: 2x^2 #2: 7z #3: 5(x+2) #4: (m+n)(m-n)

**Math**

this is a perfect square. (x-y)^2 = x^2-2xy+y^2 Now just substitute in x = 3b y = 4a

**Geometry**

depends on which direction the plane is heading. The speed could be anywhere between 250 and 350 mph.

**ctpd**

if it's a circular sector, then it's 2r+s where s is the arc length subtended.

**Maths**

assuming you mean whole numbers, 1+49 = 50 the smallest sum is 7+7 = 14 this is just the same as noting that the minimum perimeter of a rectangle with a given area is when it's a square.

**Algebra**

you'll have to do the drawings yourself. Not too hard, I expect. For scaling the figure, just multiply all the coordinates by the scale factor (2 or 1/2) and plot the new points. for scaling by 2, then (1,1) -> (2,2) (-3,1) -> (-6,2) and so on. No algebra involved at...

**Algebra**

well, 5^(2x) = (5^2)^x = 25^x so, what do you think?

**math**

----1 = 1 draw the number line place a closed circle (dot) at 1 shade to the left

**Algebra**

I assume you mean x/(x-2) + (x-1)/(x+1) = -1 using a common denominator of (x-2)(x+1), we have x(x+1) + (x-1)(x-2) = -1(x-2)(x+1) 3x(x-1) = 0 x = 0 or 1

**Math pls**

plot the two points. The slope is the change in y divided by the change in x. y changes from 2 to -2 x changes from 6 to 4 so, the slope is (-2-2)/(4-6) = -4/-2 = 2

**Algebra check answers?**

the slope is (5+2)/(-3+4) = 7, not 1/7 so, using the point-slope form, y+2 = 7(x+4) work with that. 4 1/6 = 25/6 As written, none matches. ?64 = 8

**Math - Please help ASAP!**

#1 Nope. 2*5-3 ? -7 #2 Nope. 1 ? -4(7)+3 In fact, I suspect a typo. None of the choices works.

**Maths**

did this for you last night. see related questions below.

**Algebra 2**

since the lowest value of cos(x) is -1. the lowest temperature is 3.8(-1)+2.2 = -1.6

**Math**

a negative times a negative is positive. So, (-7)(-12) = 7*12 I'm sure you can manage that ...

**math**

If the shadow length is s, and the height is h, then h = ks That means that h/s = k, a constant. So, you want s such that 6/15 = 20/s

**math**

huh? Just add them up!

**maths**

draw a diagram. It should be clear that tan? = 65/42

**Math**

what, no cubits, chains or roods?

**math - eh?**

There seems to be some context missing. You want to clarify things a bit?

**Math**

heck - just set the two equal: -x^2+9 = 3/x x^3-9x+3 = 0 cubics usually require a numeric or graphical method. I assume you have studied some of those. http://www.wolframalpha.com/input/?i=x%5E3-9x%2B3%3D0

**Math**

clearly t= 7508.4 i think is not a reasonable answer. 7500 years? 300 e^(5k) = 1500 e^(5k) = 5 5k = ln5 k = ln5/5 = 0.32 so, y(t) = 300 e^(0.32t) y(10) = 300 e^3.2 = 7360 300 e^(0.32t) = 12500 e^(0.32t) = 41.67 0.32t = ln 41.67 = 3.73 t = 3.73/0.32 = 11.65

**Math**

find k using 300 e^(5k) = 1500 use that k with t=10 finally, use that k to find t when 300 e^(kt) = 12500

**math**

50lb = 22.73kg so, you will need 1.5*22.73 = 34.1 mg . . .

**science**

150 mi/hr * 1609 m/mi * 1hr/3600s = 67 m/s

**Maths - Matrices**

oops - misspoke: A-1 = 1/2 (1 2) (1 4) So, X = (0 0) (4 4) see http://www.wolframalpha.com/input/?i=(inverse+%7B%7B4,-2%7D,%7B-1,1%7D%7D)*(2%7B%7B-4,-4%7D,%7B2,2%7D%7D)

**Maths - Matrices**

If you write this as AX = B then X = A-1B A-1 = (1 1) (1 2) now just crank it out.

**Science**

of what?

**Maths**

630 = 2^4•3•13+6 940 = 2^3•3^2•13+4 so, your number is 2^3•3•13 = 312 630 = 2*312+6 940 = 3*312+4

**math**

no, (a) has a negative slope. Rearrange things into slope-intercept form and you get 5x + y = 50 y = -5x+50 slope = -5, intercept=50 do that for the others, and it will then be clear which is what you want.

**math**

first step: which have positive slopes?

**Algebra**

you want to try that without TeX? x^n - 1/x^n = p(x - 1/x) ... where does z come in?

**Algebra**

google is your friend: https://math.stackexchange.com/questions/1967491/suppose-we-have-the-following-identity-px-1-py2-ax2-bxy-cy2-f

**Algebra**

xf(x) + f(1-x) = x(x-1)(x+1) (1-x)f(1-x) + f(1-(1-x)) = (1-x)((1-x)-1)(1-x+1) multiply the first by (1-x): x(1-x)f(x) + (1-x)f(1-x) = x(x-1)(x+1)(1-x) f(x) + (1-x)f(1-x) = (1-x)(-x)(2-x) subtract to get (x(1-x)-1)f(x) = (x(x-1)(x+1)(1-x))-((1-x)(-x)(2-x)) f(x) = -x(1-x)(x^2-x+...

**Algebra**

If y=f(x) maps a value of x to a value of y, then look at the first line. It says f(4) = -2 f(4) = 2 it cannot be both. So, (A) is not a function.

**Algebra**

if a value of x maps to two different y's, it is not a function. So, look for a line with a repeated 1st element.

**Algebra**

ya think? 3f(1/x)+(2f(x)/x)=x^2 now, if x = -2, 3f(-1/2) + 2f(-2)/-2 = 4 3f(-1/2) - f(-2) = 4 if x = -1/2, 3f(-2)+2f(-1/2)/(-1/2) = 1/4 -4f(-1/2) + 3f(-2) = 1/4 f(-2) = 67/20 ------------------------ or, we have ------------------------ 3f(1/x)+2(1/x)f(x) = x^2 3f(x) + 2xf(1/x...

**physics**

conserve momentum: 3*5 + 4*0 = 3*0 + 4v

**Math**

The number of fish in a tank decreases by x% each year. Given that the number of fish halves in 8 years, (1-x/100)^t = (1/2)^(t/8) t log(1-x/100) = t/8 log(1/2) log(1-x/100) = log(2^(-1/8)) 1 - x/100 = 2^(-1/8) x/100 = 1 - 2^(-1/8) x = 100(1 - 2^(-1/8)) = 8.3

**Math Help TIMED!**

but yes, it is A.

**Algebra 2**

not quite... 5?8^(4x) = 376 8^(4x) = 75.2 4x log8 = log75.2 x = log75.2/(4log8) or, since 4log8 = log4096, x = log409675.2

**math**

you are correct. The question is, why did you use that value? Just think it through, and you should see why it is correct.

**Chemistry**

start by recalling that 1 mole occupies 22.4L (dm^3) at STP Then use the fact that PV=kT since all the items are given in the same units, the formula works just fine. Just find the one which matches the standard values.

**trigonometry**

is the building uphill or downhill from the post? If the building is downhill from the post, at a horizontal distance of x, then let a = vertical distance from the base of the building to the base of the post x = horizontal distance between building and post h = height of post...

**trigonometry**

Draw a diagram. Let a = distance from A to the base of the tower b = distance from B to the base of the tower h = height of the tower Then we have b^2 = a^2+50^2 h/b = tan18° h/a = tan30° Now you can find a,b and thus h.

**Science**

google is your friend: https://socratic.org/questions/write-a-balanced-ionic-equation-to-represent-the-reaction-between-sulfur-dioxide

**Maths**

clearly, (7 1/4)*(1 3/5) = 29/4 * 8/5 = ?