Thursday

October 8, 2015
Total # Posts: 34,415

**Chemistry**

(a) 87.073 -> 87.1 -> 90 (b) 4.3621 -> 4.36 -> 4 and so on what do you get?
*September 18, 2015*

**Physics**

remember the law of cosines? the angle between the two headings is 55.4° So, figuring distance = speed * time, we have your distance apart (z) after 2.3 hours is z^2 = (730*2.3)^2 + (610*2.3)^2 - 2(730*2.3)(610*2.3)cos55.4° z = 1453 m I suspect you meant mi (miles), ...
*September 18, 2015*

**trigonometry**

Looks good to me.
*September 18, 2015*

**Logarithm help**

the fraction left after n pages is p(n) = 0.995^(n/10) Now you can use that to answer the other two parts.
*September 18, 2015*

**Logarithm help please**

If you mean log(4y) = x + log(4) Then you have log(4y/4) = x log(y) = x x = 10^y Assuming the usual lack of care with parentheses, I'll guess you mean 5^(1+x) = 2^(1-x) 5*5^x = 2 * 1/2^x (5/2) = 1/(10^x) 10^x = 2/5 x = log(2/5)
*September 18, 2015*

**calculus**

y = (x^2 sinx) / (x+2)(x^2-1) = (x^2 sinx)/(x^3+2x^2-x-2) Woah ... this will get messy d/dx (x^2 sinx) = 2x sinx + x^2 cosx d/dx (x+2)(x^2-1) = 3x^2+4x-1 y' = (2x sinx + x^2 cosx)(x^3+2x^2-x-2) - (x^2 sinx)(3x^2+4x-1...
*September 18, 2015*

**math**

Starting with x blooms, we have (1 - 3/14 - (2/5)(11/14))x = 66 33/70 x = 66 x = 140
*September 18, 2015*

**Physics**

the plane flies 445*1.97 = 876.65 km So, in still air, its position would be (270.9,833.7) So, you want Vx * 1.97 = 0-270.9 Vy * 1.97 = 785-833.7 Now you know Vx and Vy, so you can find V and its direction
*September 18, 2015*

**circle trigonometry**

sinθ = y/r So, in QII, y = 2 r = 3 x = -√5 Now, cosθ = x/r = ?
*September 18, 2015*

**Physics**

If we assume that the ball just grazes the hoop and somehow falls in, we can work it out like that. In real life, of course, the ball will rise above the hoop and fall in from somewhere above it, but since no such information was given, we have to just assume that y(0) = 0 y(8...
*September 18, 2015*

**Algebra**

clearly it is (C) since substitute means put in the place of
*September 18, 2015*

**mathematics**

well, which is it? 8 or 17?
*September 18, 2015*

**Math**

I think you used x for multiplication, rather than a variable. If not, then Shawn's solution finds the value of x which makes the equation true. I was under the impression you were just trying to evaluate an expression.
*September 18, 2015*

**Math**

-12/3x(-8+(-4)^2-6)+2 -4(-8+16-6)+2 -4(2)+2 -8+2 -6
*September 18, 2015*

**Math**

(1+.09/2)^(2t) = 3 Now just solve for t (years)
*September 18, 2015*

**Math**

(1+.05/12)^12 = 1.05116 So, that would be 5.116%
*September 18, 2015*

**Calculus**

a(s) = πr^2 = π(3√s)^2 = 9πs a(5) = 45π Don't forget your Algebra I now that you're taking calculus. You will be using it a lot!!
*September 18, 2015*

**Math**

159mi/3hr = 53 mi/hr
*September 18, 2015*

**PHYSICS**

v(t) = dx/dt = u+at Now go for it. I hope you have a value for a.
*September 18, 2015*

**science**

need to what? meditate? learn? rant? sing? dance? google is your friend...
*September 18, 2015*

**math**

just add up the interest on each part. If $x was at 8%, the rest (8000-x) was at 10%. So, .08x + .10(8000-x) = 700
*September 18, 2015*

**shaw**

mass
*September 18, 2015*

**physics**

well, 1J = 1N-m So, since you want meters, 42x10^6 N-m/500N = ? m
*September 18, 2015*

**math**

.20*.25*80 + .10*(1-.25)*80 ------------------------------- = 1/8 = 12.5% 80
*September 18, 2015*

**math**

I think you meant whole1
*September 18, 2015*

**Chemistry**

Looks ok to me.
*September 18, 2015*

**physics**

you want t when 2.5t^2 = 1800
*September 18, 2015*

**physics**

The horizontal speed does not matter. As you know, the max height is v^2/2g where v is the vertical speed. So, plug in your numbers.
*September 18, 2015*

**Science**

since F = GMm/r^2, twice the radius means 1/4 the force.
*September 18, 2015*

**Maths**

actually, 6840 is the Least common multiple. There is no greatest multiple.
*September 18, 2015*

**Maths**

120 = 2^3 3 5 180 = 2^2 3^2 5 190 = 2 5 19 So, take the highest power of each prime common to all numbers: 2 5 = 10 No other (larger) combination of those prime factors will divide all three numbers.
*September 18, 2015*

**algebra**

exclude values where the denominator is zero.
*September 18, 2015*

**Grade 11 math**

that would be 1.1/10.9
*September 17, 2015*

**Calculus**

(1-cotx)/(cosx-sinx) = ((sin-cos)/sin) / (cos-sin) = -1/sin --> -√2
*September 17, 2015*

**math**

2/(5m-14) = 9+3/(5m) That gets nasty. How about 2/(5m)-14 = 9+3/(5m) m = -1/115 probably not. How about (2/5)m-14 = 9+(3/5)m m = -115 Parentheses make a difference.
*September 17, 2015*

**Algebra 2**

√(120x^5y^4) √4√30 √x^4√x √y^4 = 2x^2y^2 √(30x) You were close, but changed a √2 to 2.
*September 17, 2015*

**Math**

integer
*September 17, 2015*

**math**

well, 6 min is 1/10 of an hour, so ...
*September 17, 2015*

**math**

draw a line of 3 squares. Now draw 8 more, so you wind up with 9 lines of 3. Or, 3 columns of 9
*September 17, 2015*

**math**

you can't "solve" a linear equation. It just describes a function. Now, if you want to see where the two functions are the same, you need x+4 = -2x+1 3x = 3 x = 1 so, y=5 If you want to find the root, where y=0, then just set y=0 and solve for x: 0 = x+4 x = -4
*September 17, 2015*

**algebra**

x + 5x+1 = 25
*September 17, 2015*

**Math**

You need the quadratic formula for this, since it does not factor over rational numbers. Now, 4x^2-4x+1 = (2x-1)(2x-1)
*September 17, 2015*

**8th grade math**

8.5 = 14 - 1/32 x 1/32 x = 14 - 8.5 1/32 x = 5.5 x = 5.5 * 32
*September 17, 2015*

**math**

I don't see any expressions; just sets of three numbers. Ahhh. If you mean 40.1 * 10^26 4.1 * 10^27 0.411 * 10^26 0.04001 * 10^25 then convet them all to 10^25 and you have 401 * 10^25 410 * 10^25 4.1 * 10^25 0.04001 * 10^25 Now it should be clear.
*September 17, 2015*

**Math**

700,000 -300,000 ------------- 400,000 That's low, because we rounded down the minuend and rounded up the subtrahend.
*September 17, 2015*

**prealgebra**

41/(35x)
*September 17, 2015*

**Math**

100,000 = 10^5 1,000,000 = 10^6 10^6/10^5 = 10 Or, just count the zeros. Subtract the zeros from the smaller number and see what's left of the larger number.
*September 17, 2015*

**Math**

convert each ratio to a decimal, then compare. For example, 35/84 = 0.417 laps/min now do the others
*September 17, 2015*

**Math**

2(w + 3w) = 80 w = 10 The garden is 10x30 Now you can find the area, and of course, the number of pavers. Don't forget the corners.
*September 17, 2015*

**Algebra 2**

What happened to your y's? Typo, I'd guess So far, so good: (1/27x^3)/ (1/y^9) = (1/27x^3) * y^9 = y^9/27x^3 Or, you could have done (3x/y^3)^-3 = (y^3/3x)^3 = y^9/27x^3
*September 17, 2015*

**chemistry**

CaO + 2HNO3 = Ca(NO3)2 + H2O
*September 17, 2015*

**math**

since distance = speed * time, If train #1's speed is x, 4x = 2(x+42)
*September 17, 2015*

**Algebra**

I think you will get a better result from (x + x+1)4=17 It's confusing if you use x for both multiplication and a variable. And, as we are looking for Frodo's rate, I'd use 4(f + f-1) = 17
*September 17, 2015*

**Maths**

There's a nice discussion of this topic at http://mathforum.org/dr.math/faq/faq.0.to.0.power.html Sorry -- it's turtles all the way down.
*September 17, 2015*

**Math**

3a(3a-2b)+b^2-c^2 9a^2-6ab+b^2-c^2 (3a-b)^2-c^2 (3a-b+c)(3a-b-c)
*September 17, 2015*

**mamacao elementary school**

clearly C=0 or 1 or 5 or 6 Probably not 0, eh? C cannot B 1, since then we must have ABC*1 = ABC. AB5*5 = DB5 AB6*6 = DB6 If A is more than 1, there will be a carry in A*5, so A=1 There is clearly a carry from B*5 or B*6, so 1B5*5 = 2B5 1B6*6 = 2B6 If C=5, B must be even. ...
*September 17, 2015*

**trigonometry**

Sitintile senior secondary school is not the subject. A tutor who is in a hurry or bored might just ignore a posting that appears bogus, or maybe posted by someone who cannot follow simple instructions. Did you draw a diagram? Review your basic trig functions, and you will see...
*September 17, 2015*

**analytic geometry**

Your font got garbled in the copy/paste. What is Î± supposed to mean?
*September 17, 2015*

**Intermediate Algebra (math)**

Well, since this is a fairly straightforward expression, just divide each term of the numerator by the denominator. Just as in (20+30+50)/10 = 20/10 + 30/10 + 50/10, you have (8x^2y^2+4xy^2-12y^2) ÷ 4xy^2 = 8x^2y^2/4xy^2 + 4xy^2/4xy^2 - 12y^2/4xy^2 = 2x + 1 - 3/x or, if...
*September 17, 2015*

**Math**

well, A = bh So, plug in your numbers and find b.
*September 17, 2015*

**math**

s+f = 74 (f-10)/(s-10) = 7/2 So, solve for s and f, and then evaluate (f+10)/(s+10)
*September 17, 2015*

**algebra**

any values of p that make the denominator zero must be excluded from the domain.
*September 17, 2015*

**Physics**

h(t) = 1.50 + 17.0t - 4.9t^2 Now just find t when h(t) = 0
*September 17, 2015*

**Math**

clearly the answer is 5*20
*September 17, 2015*

**Geometry**

h/35 = 6/1
*September 17, 2015*

**math help needed!**

see your previous post: http://www.jiskha.com/display.cgi?id=1442450922
*September 17, 2015*

**algebra**

You figured out min/mile. Keep track of the units! 16964.6 in/min * 1mi/63360in = 0.2677 mi/min Now multiply that by 60min/hr to get mi/hr.
*September 16, 2015*

**math**

f = 1/2 (r+6.5) Solve for what? We already have an equation solving for f.
*September 16, 2015*

**math**

"the number times 17" means "y times 17" means 17y So, you have y-6 = 17y
*September 16, 2015*

**precalc**

Didn't we just do one of these? sec 3π/10 = 17/10, csc 3π/10 = 17/14 means r=17 x=10 y=14 csc 43π/10 = csc(4π + 3π/10) = csc 3π/10 sec 2π/10 = sec(π/2 - 3π/10) = csc 3π/10 cot -12π/10 = -cot 12π/10 = -cot(π+2...
*September 16, 2015*

**math,**

That's right. For every additional °C, it takes 7 more Joules. So, your table looks like °C J 26 7 27 14 28 21 ... h(t) = 7(t-25)
*September 16, 2015*

**math**

g(t) = t^2+t g'(t) = 2t+1, so g'(-1) = 2(-1)+1
*September 16, 2015*

**math please help me!**

See the graph at http://www.wolframalpha.com/input/?i=x+lnx As for your estimate of f'(1), it is clearly approaching 1.0 (not sure how you got that last value of 0) f(3) = 3 ln3 = 3.295 f'(3) ≈ [f(3.01)-f(3)]/0.01 = (3.317-3.295)/.01 = 2.18 You can see that the ...
*September 16, 2015*

**Mechanics NYA**

75 km/hr = 20.833 m/s so, at 75km/hr, the car travels 20.833 * 0.116 m Then, it takes 20.833/5.4 seconds to stop, and the distance traveled while braking is 20.833t - 2.7t^2 where t is the above stopping time.
*September 16, 2015*

**Math**

In word problems, you can be pretty sure that "of" means times. 1/2 of 6 is the same as 1/2 * 6 = 3 So, can you multiply 1/10 by 200?
*September 16, 2015*

**Math**

biweekly is every two weeks. That's 10 days of 8 hours each, right? 10*8*8.38 per paycheck. Now convert that to monthly, remembering that there are 26 paychecks to cover 12 months.
*September 16, 2015*

**math**

well, you correctly determined that 6 mi/hr is 1/10 mi/min, so 1 mi/hr is the same as 1/60 mi/min, right? y = 2.5 + 1/60 t for 40<t<65. Actually, some of those inequalities should be <= just to make D(t) continuous.
*September 16, 2015*

**Math Grade 5**

In word problems, you can be pretty sure that "of" means times. 1/2 of 6 is the same as 1/2 * 6 = 3 So, can you multiply 1/0 by 200?
*September 16, 2015*

**precalc**

3. csc 64° = = r/y = 10/√19 4. csc -26° = -csc(26°) = -sec(64°) = -r/x = -10/√19 5. sec 244° = sec(180°+64°) = -sec(64°) = -r/x = -10/√19 For #4, recall that 64° and 26° are complementary angles. So, swap func and co-...
*September 16, 2015*

**precalc**

since sin = y/r and cos = x/r, you have x = √19 y = 9 r = 10 Now look at the other functions. tan = y/x sec = r/x etc.
*September 16, 2015*

**Science**

30.0m/s * 0.80h * 3600s/h * 1km/1000m = 86.4km
*September 16, 2015*

**Algebra**

complex roots come in conjugate pairs, so if -6-8i is a root, so is -6+8i. With those two roots, the least degree polynomial will just be degree 2, so we have y = (x-(-6-8i))(x-(-6+8i)) = (x+6+8i)(x+6-8i) = (x+6)^2 - (8i)^2 = x^2+12x+36+64 = x^2+12x+100 check here: http://www....
*September 16, 2015*

**Pre-Calculus**

the parabola with directrix at x=p and vertex at (0,0), and focus at x = -p is y^2 = 4px. You have a parabola with 4p = -4, so p = -1 and it is shifted by (2,-1). So, vertex = (2,-1) focus = (1,-1) directrix: x = 3 See here for confirmation: http://www.wolframalpha.com/input/?...
*September 16, 2015*

**Algebra**

To find the number of $5 bills, add up the value of all the bills and solve for f: 10*11 + 5*f + 1*(f+7) = 267
*September 16, 2015*

**Math**

If there are w white beads, then w + 6w+1 = 50
*September 16, 2015*

**Mathematics**

The width of the water surface when it has depth y is 6/5 y. So, the cross-sectional area is (1/2)(y)(6/5 y) = 3/5 y^2 Thus, the volume at depth y is 120y^2 cm^3 We have dv/dt = 240y dy/dt Now plug in the numbers and we have dv/dt = 240(20)(-1) = -4800 cm^3/min Or, 4.8 L/min
*September 16, 2015*

**Algebra 2**

(a-4)/(a^6) = a/a^6 - 4/a^6 = 1/a^5 - 4/a^6 or a^-5 + 4a^-6 Not that it looks much simplified...
*September 16, 2015*

**Math**

7+10^2*3-54 7+100*3-54 7+300-54 307-54 253
*September 16, 2015*

**Geometry**

angle: x complement: 90-x x = 26+3(90-x) x = 74
*September 16, 2015*

**Geometry**

You are correct
*September 16, 2015*

**algebra**

seems clear that if you know what a decimal place is, and can count to two, then you'd get pretty close on the first try. Then it's just a matter of rounding.
*September 16, 2015*

**algebra**

what's with the 12-x? "12 times" means 12* x + 12x + 12x-20 = 180 You seem to have a problem distinguishing between subtraction and multiplication.
*September 16, 2015*

**algebra**

200 + .05s = 475
*September 16, 2015*

**Math**

almost anything with an exponent between -7 and +7 Looks like C to me.
*September 16, 2015*

**maths**

How about 1 and 6? -6 + 1 = -5 That help?
*September 16, 2015*

**maths**

which two factors of 6 differ by 5?
*September 16, 2015*

**maths**

Expand and collect terms: (x-2)^2+3x-2=(x+3)^2 x^2-4x+4+3x-2 = x^2+6x+9 x^2-x^2-4x+3x-6x+4-2-9 = 0 ...
*September 16, 2015*

**Physics**

In x-y coordinates, A = (-13.156,4.788) B = (0,11) C = (-9.830,-6.883) D = (16.070,-19.151 Add them all up and you get (-6.916,-21.246) The resultant thus has magnitude √(6.916^2 + 21.246^2) = 22.343 and direction θ where tanθ = -21.246/-6.916 = 71.97° in ...
*September 16, 2015*

**science**

momentum before: mv momentum after: m(-v) now just subtract to get the change.
*September 16, 2015*

**maths**

which two factors of 18 add to 11?
*September 16, 2015*