# Posts by STEVE

Total # Posts: 54,358

**Math**

Vs*Ts = 88 (Vs-13)(Ts+4) = 72 22*4 = 88 9*8 = 72

**Physics**

add the two velocities in a right triangle. ?(1^2+3^2) = ?10 mi/hr 300 yds = 300/1760 = 0.17 miles so, it will take 0.17 hours to cross the river. Since the river flows 3 times as fast as he swims, he will wind up 3*0.17 = 0.51 miles downstream.

**calculus**

correct

**calculus**

yes. since 3=?3*?3, ?3/3 ?3/(?3*?3) = 1/?3

**calculus**

3cotx - ?3 = 0 3cotx = = ?3 cotx = 1/?3 Now it's time to review the "standard" angles whose trig functions are easy to remember. One of these is 60°, where cot60° = 1/?3

**Math plz help**

#2. Remember that |x| = x if x >= 0 |x| = -x if x < 0 So, you have |y+4| < 1 so, either y+4 >= 0, meaning y >= -4 or y+4 < 0, meaning y < -4 If y >= -4 y+4 < 1 y < -3 If y < -4 -(y+4) < 1 -y-4 < 1 -5 < y But also, we started with y <...

**Math plz help**

clearly not 2D. Just plug in y=2 |2+4| = |6| = 6 Bzzzt #3 is also wrong. You forgot to divide by 2. |2r| = 12, not |r| = 12 #4 is correct

**Math**

There is no unique solution. This is just the equation of an hyperbola. Some integer solutions are (-3,3) (0,-9) (1,19) (4,7) y = (10x+9)/(2x-1)

**fire dynamics**

no idea. how fast does it burn?

**fire dynamics**

1 gallon = 231 in^3. The fuel depth in the spill is volume/area: 3500*231/2500? = 102.94 in so, at 6 in/hr, it will burn for 102.94/6 = 17.157 hours

**algebra**

KE = 1/2 mv^2 2KE = mv^2 m = 2KE/v^2 C = 0.5x+10 C-10 = 0.5x x = 2C-20

**Advanced Algebra**

Bart made some home improvements for $6,091 using a six-month deferred payment plan with an interest rate of 23.79%. What is the balance after the deferment period if no payments are made? A.$6,091.00 B.$6,776.90 C.$7,540.05 D.$6,852.40 My answer is D

**Advanced Algebra**

Jeffrey earned a gross income of $51,280 last year. He made $1,746.83 in student loan interest deductions, donated $2,914 to his favorite charities and paid $3,941.47 in home mortgage interest. Jeffrey claims a standard deduction of $11,400 for himself and his non-working ...

**math**

well, only b is rational ...

**Pre-Calculus**

If x is liters and y is gallons, then y = kx k = 14/53 now plug in y=25 Or, since the ratio is always the same, and you have (25/14) as many gallons, you will have (25/14) * 53 liters

**Pre-Calculus**

w = kz so, w/z = k, a constant. So, you want w such that w/3 = 9/-6

**Pre-Calculus**

well, y=kx, so plug in the values.

**Pre-Calculus**

true.

**Geometry**

well, the diagonal of a square of side s is s?2, so what do you think?

**math**

126423746278

**algebra**

3+4a+6b-8-5 4a+6b + 3-8-5 now do you get it?

**Maths**

48 = 8*6, so 8 times as much flour. 8 * 3/5 = ?

**AP Calculus**

d is false. The others are all true. See http://www.wolframalpha.com/input/?i=(5x%5E3-5x%5E2-10x)%2F(2x%5E5-2x)

**Physical**

.2 cm^3 * 2.7g/cm^3 * 6.02*10^23atoms/27.0g = 1.204*10^22 atoms

**math**

One number is x, the other is 31-x 2/3 x = 5/8 (31-x) Now just solve for x and you're almost done

**Maths**

1/4 of 4/5 is 1/5, so 3/5 remain in the tank 3/5 * 32 = ?

**math**

0.37x = 0.0925 x = 0.0925/0.37 = 0.25

**Physics**

how long does it take to fall 1.02m? 4.9t^2 = 1.02 the horizontal speed does not matter.

**Maths**

You sure there are not 17 balls? Then the probabilities would be 8/17 and 9/17 Much messier with 18 balls, but you can see how to divide it up.

**Math**

This has popped up two or three times in the last few days. Don't know why it doesn't appear in the list of related questions. Try here: https://www.jiskha.com/display.cgi?id=1506885649

**physics**

watts = energy/time so, use this to find the energy (watch the units!) PE = mgh

**Chemistry**

9.45?m = 9.45*10^-4 cm each inch is 2.54cm so, 9.45*10^-4cm * 1in/2.54cm = ? in

**Chemistry**

how many meters in 0.45 miles? If that number is N, then it will take (N/1500)*(14'34.56")

**math**

There are lots of useful online calculators. One such, for this topic, is at http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html

**Algebra 1**

|| is ALWAYS positive h(1) = |1-7*1| = |1-7| = |-6| = 6 h(9) = |1-63| = |-62| = 62 remember!!! |N| = N if N >= 0 |N| = -N if N < 0

**Algebra 1**

nope. g(9) = -9^2+10*9-3 = -81+90-3 ... g(-1) = -(-1)^2+10(-1)-3 = -1-10-3 ... g(-3) = -(-3)^2+10(-3)-3 = -9-30-3 ...

**Geometry**

where are H and J in relation to R and N?

**Calculus**

#1 f(x) = (1-x)/(1+x) and g(x) = x/(1-x) f(g) = (1-g)/(1+g) = (1-(x/(1-x))/(1+(x/(1-x)) = 1-2x while the domain of 1-2x is all reals, g is undefined for x=1, so that must be excluded from the composite as well. #2 multiply by the "conjugate" (?(x^2+8)-3)/(x-1) * (?(x...

**Algebra 1**

correct

**Algebra 1**

since I have no idea what f is, and g(x) contains no other x's, it's hard to say. Try proofreading before posting.

**Algebra 1**

just plug in the values for x everywhere in the equation. f(60) = 9/5 * 60 + 32 = 108+32 = 140 and so on

**Physics**

It does not matter how far away the person is standing (as long as it's not 0 distance!). If you draw a ray from the top of the person to the mirror and back to the person, the point that the person sees is exactly twice as far down as where the reflection is in the mirror...

**Math**

hard to say, since you don't show your work. One way is substitution. x = 7-5y-3z, so using that in the last two equations, you get 2(7-5y-3z)+y+4z = 1 2(7-5y-3z)-y+2z = 1 shuffling things about, that gives 9y+2z = 13 11y+4z = 13 Now, since 2z = 13-9y, use that to get 11y+...

**Calculas**

If you meant what you wrote, then the domain is all reals except x=0 If you meant y=1/(x-7) then the domain is all reals except x=7. In other words, all reals except where the denominator is zero.

**maths**

100/25 x^9/x^5 y^5/y^4 = 4x^4y

**math**

just look up the conversions. For example, 39.5 ft * 1yd/3ft = 13 1/6 yd 47tsp * 1cup/8tsp = 5 7/8 cup

**Math problem help**

doubling the 1st equation, we have 6/x + 4/y = 4/3 8/x - 4/y = 2/9 add them up to get 14/x = 14/9 x = 9 Now just plug that in to get y=6

**math**

1/2 + 1/3 = 5/6 2/3 of the remaining 1/6 is 1/9 That means that 1/18 is left x/18 = 20 x = 360

**MATH HELP PLEASE**

seems like this one went by yesterday. But, it's not in the related questions, so, ignoring the hint, we have x^2+y^2+z^2 = 9 3x^2-y^2-z^2 = 7 0x^2+y^2+2z^2 = 6 adding #1 to #2, we have x^2+y^2+z^2 = 9 4x^2+0y^2+0z^2 = 16 so, 4x^2=16 --> x^2 = 4 --> x = 2 Since all ...

**College Algebra**

s = q-4 In 7 years, then, (q+7) + (q-4+7) = 64 ...

**maths**

to find x, solve 5^2 + (x+5)^2 = (x+8)^2 25+x^2+10x+25 = x^2+16x+64 6x+14 = 0 x = -7/3 So, the area is (5)(5-7/3) = 5*8/3 = 13 1/3 m^2

**Math**

f?g = f(g) = g^2+2g-8 = (2x-6)^2+2(x-6)-8 now just expand that out if you must.

**maths**

a = 1/2 r^2 ? 12 to 4 is 1/3 of the way around, so the area is 1/2 * 3.5^2 * 2?/3 = 6.125? cm

**maths**

so, change 7-2 to 7-(-2) geez

**maths**

8.1*10^7 / 9*10^2 = (8.1/9)*10^(7-2) = 0.9*10^5 = 9.0*10^4 he would have had 3/4 of the origianl amount, or 3/4 * 300 = 225

**Physics**

s = 1/2 at^2, so 1/2 * 0.5 * t^2 = 100 t^2 = 400 t = 20 s assuming the acceleration is in m/s^2

**maths**

2^(3x) = 2^(5x-9) 3x = 5x-9 2x = 9 x = 9/2 10^x = 10000 = 10^4 x = 4

**Maths**

cotA = cosA/sinA cosA = cotA/cscA = cotA/?(1+cot^2 A)

**Math**

Try using math symbols. I believe you meant f(x) = x^4-4x^3-8x^2-7x+1 No idea what "Tapos" means, but 2x^3+5x^2-10x+16 used as a divisor does not leave a remainder of 3. Also, what does "k" have to do with any of the other stuff? Maybe you can fill in the ...

**linguistics**

Q: What is the difference between theory and practice? A: In theory, there is no difference, but in practice, there is.

**Math**

the same - both are linear measurements

**Algebra**

If y = mx+b, plug in the points to get 1/2 m + b = -3/2 -1/2 m + b = 1/2 add them together to get 2b = -1 b = -1/2 subtract them to get m = -2 y = mx+b = -2x - 1/2 or, consider the slope of the line: (y2-y1)/(x2-x1) = (1/2+3/2)/(-1/2-1/2) = -2 Now use the point-slope form to ...

**Math**

the price alone was 100% of what was paid, so what was added?

**Math**

the change was $1 so, what fraction of $4 is that? or, 5/4 = 1.25, so 5 = 1.25 * 4

**Maths**

The two courses are 90 degrees apart, so it's just a matter of figuring the angles of the right triangle. If the angle made by the 1st ship is ?, then the bearing of ship 2 from ship 1 is just (157+180-?)°

**math**

Assuming that the 1st letters are in sequence around S, the angles follow LSO=LSP+PSO PSN=PSO+OSN That means LSP+PSO=PSO+OSN so LSP=OSN Now just change that to a 2-column proof.

**Geometry**

Huh? That is the definition of a linear pair -- the two angles form a straight angle.

**Math**

"sin" is often used as a shorthand way of writing sin? technically, "sin" by itself is just the name of the function, and it has no value until a ? is specified. Sometimes when manipulating a long equation or expression, the ? is assumed throughout, and not...

**Algebra**

on the number line, > (greater) means "to the right of" < (less) means "to the left of so, you wold graph it by shading everything to the right of -5 AND to the left of 2 In other words, the segment between -5 and 2 ... -6 -5 (...) 2 3 ...

**algebra**

5s-3p = fp+12 5s = 3p+fp+12 5s-12 = (3+f)p (5s-12)/(3+f) = p

**Physics**

conserve momentum. That means m1*v1 + m2*v2 = mv 25*8 + 55*0 = (25+55)v

**Advanced Algebra**

thank you

**Advanced Algebra**

I disagree. If she claims the standard deduction, she cannot file a Schedule A as well, so she cannot deduct the interest and charity. I pick C

**Advanced Algebra**

Amanda earned a gross income of $37,250 last year. She made $489.78 in IRA contributions, donated $782 to her favorite charity and paid $1,276.65 in home mortgage interest. If Amanda claims a standard deduction of $5,700 and her exemption is $3,650, what is her taxable income...

**maths**

see "neha"'s post -- the one after yours...

**maths**

just plug and chug a+b = 2cosx+i sinx + 2cosy + i siny = 2(cosx+cosy) + (sinx+siny)i Now, (sinx+cosx)^2 = sin^2x+2sinx cosx+cos^2x = 1+2sinx cosx similarly, (siny+cosy)^2 = 1+2siny cosy Since 2^2-b^2 = (a+b)(a-b), we have (sinx+cosx)^2 - (siny+cosy)^2 = ((sinx+cosx)+(siny+cosy...

**Algebra**

6000r = 390 r = 390/6000 = 0.065 or 6.5%

**Chemistry**

Say you have 1 gram of Lithium. If x grams have mass 6.02, then 6.02x + 7.02(1-x) = 6.94 x = .08 so, 8% of Li is the lighter isotope. Makes sense, since 6.94 is so much closer to the heavier value.

**Physic**

I thought it was 42 ...

**Geometry**

Rubbish. Did you actually plot the points? Let's call the midpoint M. M is just as far from A as it is from B. So, if you consider the coordinates, M-A = B-M Or, B = 2M-A = 2(2,-9)-(4,10) = (4,-18)-(4,10) = (0,-28) Or, in other words, moving from A to M caused x to go from...

**geometry**

Surely you can see that the exterior angles of regular polygons with a different number of sides cannot be the same. Try drawing something easy, like a square and a pentagon. As you travel around the outside of a polygon, you keep turning by the same angle. One trip around ...

**Math**

but first change .1x to .01x ...

**Math**

for (2-x) > 0, f(x) = 1 for (2-x) < 0, f(x) = -1 so, no zeros, domain is all reals except x=2, range is {-1,1} http://www.wolframalpha.com/input/?i=%7C2-x%7C%2F(2-x)

**Math**

no idea. what is the function?

**math**

blank must be an even digit

**algebra 2**

no idea. what is the objective function?

**Math**

12/-4 = -3 -26/12 = -3 so, clearly An+1 = An * -3 Now you know you have a = -4 r = -3 and use your formula to get the 5th term.

**Math**

Let u = sin^3(x) du = 3 sin^2(x) cos(x) dx dv = e^(2x) v = 1/2 e^(2x) ?u dv = uv - ?v du = 1/2 e^(2x) sin^3(x) - 3/2 ?e^(2x) sin^2(x) cosx dx = 1/2 e^(2x) sin^3(x) - 3/2 ?e^(2x)cosx dx - 3/2 ?e^(2x) cos^3(x) dx Pull the same trick again, and you will have 3/4 of the original ...

**Math**

you need to get rid of that pesky ln(1+x). So, u = ln(1+x) du = 1/(1+x) dx dv = x dx v = 1/2 x^2 ?u dv = uv - ?v du = 1/2 x^2 ln(1+x) - 1/2 ?x^2/(1+x) dx which is not so hard, eh?

**Math**

?x^3 cos(x^2) dx If you let u=x^2, you have du = 2x dx and the integral is 1/2 ?[?/2,?] u cos(u) du Now you can tackle that using integration by parts.

**Math**

x sinx cosx = 1/2 x sin2x u = x/2 du = 1/2 dx dv = sin2x dx v = -1/2 cos2x ?u dv = uv - v du = -1/4 x cos2x + 1/4 ?cos2x dx = -1/4 x cos2x + 1/8 sin2x + C using the limits of integration, we have (-1/4 ? + 0) - (0 +0) = -?/4

**Math**

Cute. Let u = xe^(2x) du = e^(2x)(1+2x) dv = 1/(1+2x)^2 v = (-1/2)/(1+2x) ?u dv = uv - ?v du = -(xe^(2x))/(2(1+2x)) - ?(-1/2)e^(2x) dx = -(xe^(2x))/(2(1+2x)) + e^(2x)/4 = e^(2x)/(4(1+2x)) + C

**Advanced Algebra**

Sharon purchased a sprinkler system for $1,950 using a six-month deferred payment plan. The interest rate after the introductory period is 23.99%. No down payment is required, but there is a minimum monthly payment of $25. What is the balance at the beginning of the seventh ...

**Advanced Algebra**

Krystal bought a refrigerator from a rental center for $1,050. She makes 16 monthly payments of $112.75 with her credit card. The rental center charges $1.25 for every purchase made with a credit card. What is the total cost of the refrigerator? My answer is $1824 dollars $112...

**Pre-Calculus**

Oops. sin/cot = sin*tan = sin^2/cos csc/cot = 1/sin * sin/cos = 1/cos You should have said csc(2x)/cot(2x) - sin(2x)/cot(2x) = 1/cos(2x) - sin^2(2x)/cos(2x) = (1-sin^2(2x))/cos(2x) = cos^2(2x)/cos(2x) = cos(2x) or, csc-sin = (1-sin^2)/sin = cos^2/sin = cos * cot

**Pre-calc**

16/(2x+2) = 8/(x+1)

**9th grade algebra**

The b1+b2 quantity is just a number, like any other. You can divide by it, just like you divide by the 1/2... 1/2 (b1 + b 2)h = A (b1+b2)h = 2A h = 2A/(b1+b2)

**algebra - Incomplete**

more information, please?

**Math**

Not sure what "do this" means, but if you want to solve for t, then assuming you meant (5/13)t = -9 since (5/13)(13/5) = 1, then multiplying both sides by 13/5 gives you (5/13)(13/5)t = -9(13/5) t = -117/5

**physics**

s = 1/2 at^2 now plug in your acceleration and time...