# Posts by Helper

Total # Posts: 1,881

**math**

If you sketch this you will see a right triangle is formed. a = 8 b = 6 c = hypotenuse Use the Pythagorean theorem c^2 = a^2 + b^2 Solve for c, road to Bobby's house

**Calculus 1**

x^7 + y^7 = 8xy 7x^6 + 7y^6 y' = 8y + 8x y' 8x y' - 7y^6 y' = 7x^6 - 8y y'(8x - 7y^6) = 7x^6 - 8y y' = (7x^6 - 8y)/(8x - 7y^6)

**geometry**

Formula for long diameter (vertex to opposite vertex), d = (2 * side length * sin 67.5)/(sin 45) Formula for short diameter (one side to opposite side) d = ((2 * side length)/(sqrt(2))) + side length I'll do short diameter, d = (2 * 48)/(sqrt2)) + 48 d = (96)/(1.4142) + 48...

**calculus**

Like I said, more than one way to do this. I suggest follow Reiny's way.

**calculus**

Thanks Reiny. Nicky, depending on your approach, you need to use both the product rule and the chain rule (more than once). It's easy to get lost in this problem. What exactly do you not understand? Have you tried setting the problem up? One approach, start with the ...

**calculus**

Just making sure. Do you mean e^(8x^4) or e(8x^4) I've never see "e" referred to "exp" on this site, but I haven't been here long.

**calculus**

What is exp?

**math**

48a^2 + 4ab - 140b^2 Factor out 4 4(12a^2 + ab - 35b^2) 4(3a - 5b)(4a + 7b)

**geometry**

What is the figure? Depending on what the figure is, where is AC and BC ?

**math--To MathMate**

In regards to your reply to the problem that Daniel posted (f'(-pi)). I really appreciate you (and Reiny) taking the time to confirm that my answer was correct. I don't usually answer unless I am absolutely sure an answer is correct (I don't want to give wrong ...

**calculus**

All the online integration calculators I tried said that this cannot be integrated. Recheck your problem.

**Math**

80 mg = 0.08 grams 4 tablets x 20mg ea = 80 mg Looks good :)

**MATH(CALCULUS)**

Thank you so much Reiny.

**MATH(CALCULUS)**

Did you find f'(x) first? I just read your earlier post and you said you plugged -pi into 12x/(sinx+cosx) . You have to find f' first, then plug in (-pi). The derivative, f' is, (12(x sin x + sin x - x cos x + cos x)/ (sin x + cos x)^2 Then you plug in (-pi) You ...

**Math**

1 foot = 0.3048 meters 100 = ? meters

**last question!!need help!!**

Thanks so much MathMath. I did this problem so many times. After all the time I spent on this it's nice to have confirmation that my answer is correct. If Reiny reads this the same goes to you.

**last question!!need help!!**

f(x)=12x/(sinx+cosx) The derivative, f ' is, (12(x sin x + sin x - x cos x + cos x)/ (sin x + cos x)^2 Now you have to plug in (-pi) for x. I got -12 - 12pi (my post above answer), but, like I said, I did it really quick. It's late so I'm more apt to make a mistake...

**last question!!need help!!**

Is the answer -12 - 12pi? I did this real quick, and don't have time to post all the work or to double check my work, so I'm not positive this is correct. I can look at this more in the morning or maybe another tutor will answer.

**last question!!need help!!**

Did you read my post just above yours? In your first post asking this question, the one that MathMate answered 12pi, you had the problem as, f(x)=12x/sinx+cosx find f(-pie) Now you have, f(x)=12x/sinx+cosx find f'(-pie) f and f' are different. f' is the derivative...

**last question!!need help!!**

I think I see your problem. In prior posts you had, f(x)=12x/sinx+cosx find f(-pie) Now, you have f', the derivative. f'(-pie). Which is it?

**last question!!need help!!**

Please see your prior post. If you know the answer, why are you asking? Also, it would help if you posted the answer you think it is, then a tutor might have a better understanding of what is maybe being misunderstood.

**need some help!!!**

From your previous post, which MathMate answered. f(x) = 12x/(sinx + cosx) for -pi calculus-correction - MathMate, Thursday, February 24, 2011 at 9:45pm The required problem was f(-π) = 12(-π)/(0+(-1)) = 12π 12pi is the answer. You have said that this is not the...

**Algebra 2**

Pasted from previous post by PsyDag, Since it is not an equation, I cannot solve it for you, but I can help you to simplify it. Get rid of the fractions by multiplying everything by 16. I corrected the -1 to +1. x^4 + 6x^3 + 2x^2 + 16 - 9x^4 + 14x^2 - 16 Combine like terms. If...

**Algebra**

The slope-intercept form of an equation is, y = mx + b m = the slope b = the y-intercept You need to solve your equation for y, for the equation to be in the slope-intercept form. 3y = 2x - 9 Divide both sides by 3, y = 2/3 x - 9/3 y = 2/3 x - 3 Now, the equation is in the ...

**Math**

L x W x H 18 x 14 x 8 Room Perimeter P = 2W + 2L P = 2(14) + 2 (18) P = 28 + 36 P = 64 Perimeter * Height P = 64, H = 8 Area to paint = 64 * 8 A = 512 sq ft 512 sq ft/256 sq ft paint coverage = gal of paint needed 512/256 = 2 gals per coat 2 gals/coat * 2 coats = ? ttl gals ...

**math**

Distance, D = Rate, R * Time, T D = y R = 15 fps T = x seconds D = RT y = 15x

**geometry**

First, you need to graph this triangle. Then, use the distance formula to find the distance between points (length of the sides). Area A = 1/2 bh

**Math**

Also, I just noticed, Type A contains (????HOW MANY) ounces of oats and (????HOW MANY)ounces of corn per pound. Type B contains (????HOW MANY)ounces of oats and (????HOW ANY)ounces of corn per pound.

**Math--Shell Missing Info**

Please recheck your problem, your are missing information. Type A and Type B are both oats and corn mixtures. Is this correct? The farmer wants to combine the two feeds so that the resulting mixture has at least (????HOW MANY POUNDS) pounds of oats and at least(????HOW MANY ...

**math**

x = amount invested at 6% y = amount invested at 8% 0.06x = interest at 0.06 0.08y = interest at 0.08 Solve simultaneously, x + y = 6400 0.08y = 2(0.06x) x = $2560 y = $3840 $153.60 = 6% int $307.20 = 8% int

**Maths**

A. The circumference of a circle is the actual length around the circle. Circumference C = 2 pi r r = 30, pi = 3.14 C = (2)(3.14)(30) C = 60(3.14) C = 188.4 for 1 lap 6 laps = 6 * C 6 laps = 6 * 188.4 meters 6 laps = ? meters B. P = 2w + 2L w = 37 cm./100 = 0.37 m L = 5.2 m P...

**S.P**

I = PRT (Interest = Principal*Rate*Time) I = 30,000 * 0.07 * 4 I = ?

**math !!!! :O**

This exact question was answered earlier today. See link. http://www.jiskha.com/display.cgi?id=1298550296

**math**

3x^2 y - 5xy + 12x y^2 - 5x y^2 - 4xy 3x^2 y + 7x y^2 - 9xy

**trig**

360 deg = circle 360/6 = 60 deg 60 deg * pi/360 = 60pi/360 = pi/3 rads

**Algebra 1**

x = Rate without wind y = Rate of the wind T = D/R 6 = 3000/(x - y) 6(x - y) = 3000 6x - 6y = 3000 5 = 3000/(x + y) 5(x + y) = 3000 5x + 5y = 3000 Solve simultaneously, 6x - 6y = 3000 5x + 5y = 3000 5 *(6x - 6y = 3000)= 30x - 30y = 15,000 6 *(5x + 5y = 3000)= 30x + 30y = 18,...

**math-Mathmate could you look at please**

I was working on this at the same tiime as you, but I arrived at a different answer. x = amt Tierra had 2x/5 = amt Tierra spent 3x/5 = amt Tierra had left y = amt Alex had 4x/5 = amt Alex spent y - 4x/5 = amt Alex had left z = amt Nico had $40 = amt Nico spent z - 40 = amt ...

**math**

I = PRT (Interest, I = Principal, P * Rate, R * Time, T P = 30,000 R = 7% = 0.07 T = 4 I = 30,000 * 0.07 * 4 I = 2100 * 4 I = 8400

**math**

h/-6 >= 5

**alg readiness**

Or, your could do, Assuming you know that a dollar is 10 dimes, etc. 1.00 = 10 dimes 4.00 = 4 * 10 dimes = 40 dimes 0.60 cents = 6 dimes 4.60 = 40 dimes + 6 dimes 4.60 = ? dimes

**alg readiness**

3/5 of a dollar = 0.60 (3/5) 4.60/0.10 = ?

**algebra**

(8.1 x 10^-9) x (4 x 10^2)? There are different ways to approach this problem I would do this problem like this, 8.1 * 4 * 10^-9 * 10^2 32.4 * 10^-7 0.00000324 32.4 with the decimal point moved 7 places to the left (since the exponent is negative)

**math 117 for bobpursley**

Ally is NOT correct.

**math**

Distance D = Rate R * Time T R = rate she rowed R + 2 = combined rate (rowing and river current) RT = D (R + 2)*6 = 16 6R + 12 = 16 6R = 4 R = 4/6 = 2/3 = 0.67 R = 0.67 km/hr rowing

**ALGEBRA**

If you asked this same question yesterday, refer to that post. I know this was answered yesterday, but I search quickly and can't find it.

**geometry**

Area of square = side s^2 100 = s^2 s = 10 The diagonals of a square bisect each other and meet at 90 degrees. The diagonals of a square bisect its angles. The diagonals of a square are perpendicular. The diagonals of a square are equal. This means that the two diagonals ...

**math**

Integration of x^2 ln(x^3+2) | = integration symbol | x^2 ln(x^3 + 2) w = x^3 + 2 dw = 3x^2 1/3 dw = x^2 1/3 | ln(w) dw Integration by parts | u dv = uv - | v du u = ln(w) dv = dw du = 1/w dw v = w 1/3 | ln(w) dw = 1/3 ln(w) w - 1/3 | w 1/w dw = 1/3 w ln(w) - 1/3 | w/w dw = 1/...

**math**

derivative of ln(x^3 + 2) f'(ln(f(x))) = 1/(f(x)) * f'(x) f'(ln(x^3 + 2)) = 1/(x^3 + 2) * 3x^2 f'(ln(x^3 + 2)) = 3x^2/(x^3 + 2) f' = 3x^2/(x^3 + 2)

**geometry**

A regular octagon has 8 equal sides P = sum of all the sides, or P = number of sides * length of side P = 8 * 9.4 P = ?

**math**

Volume of sphere, V = 4/3 pi r^3 2123 = 4/3 pi r^3 6369 = 4 pi r^3 1592.25 = pi r^3 1592.25 = (3.14)r^3 507.086 = r^3 r = 7.97432

**math**

(-3,7), (5,-1) Slope-intercept form of the equation is, y = mx + b m = slope b = y-intercept To find slope, m Slope m = (y2 - y1)/(x2 - x1) m = (-1 - 7)/(5 - (-3)) m = -8/8 = -1 To find y-intercept, b Use either point, (-3,7) and substitute the x and y values in the slope-...

**algerbra/math**

x = amount Don has "Leo has 1/5 of the amount Don has" Since Don has " x amount", then 1/5 x = amount Leo has

**algerbra/math**

x = amount Don has "Nadia has 1/2 of the amount Don has" Since Don has " x amount", then 1/2 x = amount Nadia has

**algerbra/math**

Sky, I've done two examples for you. All your problems are the same. Your turn to try the other problems. Post your answers and I will check them for you.

**math**

Or maybe the problem is , (?) 7/25 * 360 (no decimal point) = 2520/25 = 100.8 degrees

**math**

9% = 0.09 0.09 * $245 = $22.05 spent

**Math**

60% = 60/100 = 6/10 completed 10/10 - 6/10 = NOT completed

**Math**

Correct ! Good job :)

**Math**

d = number of DVDs 4d = number of CDs d + 4d = 60 5d = 60 d = ?

**Algebra 2**

2000-60P > 460 + 94p 1540 > 154p 10 > p p < 10 2000-60P < 460 + 94p 1540 < 154p 10 < p p > 10

**Algebra 2**

Your question was answered. Please don't repost without checking your original post for an answer. http://www.jiskha.com/display.cgi?id=1298423664

**math**

What shape is the container ?

**algebra 2**

Which is it -40.4t or -40.5t? First you have -40.4t, then you have -40.5t o(t) = -40.5t + 2159 -40.5t + 2159 < 1750 -40.5t < -409 t > -409/-40.5 t > 10.09877 = 10 t years after 2000 2000 + t years = ?

**math**

2 pints = 1 quart 4 cups = 1 quart Is this what you mean?

**Algebra 2**

-7x^4 + 8x^3 - 8x^2 + 3x-4 The first term in the polynomial, when it is written in decreasing order, is also the term with the biggest exponent, and is called the "leading term". The exponent on a term tells you the "degree" of the term. For instance, the ...

**Solving a system of linear Equations using Substit**

x = number of newsletter copies 0.90x = cost for mailing & printing 600 = cost for research & writing 0.90x + 600 = total cost for publishing newsletter 1.50x = total from selling newsletter 0.90x + 600 = 1.50x 0.6x = 600 x = 1000 newsletters to break-even

**Math**

In 2001, aver. price of an acre = $1132 In 2006, aver. price of an acre = $1657 a. 2001 = 0, 1132; 2006 = 5, 1657 2001 would be the starting year and 2006 would be 5 years later The ordered pairs would be, (0,1132), (5,1657) b. slope m = y2 - y1/(x2 - x1) m = 1657 - 1132/(5 - ...

**Calc**

4x - x^2 -(x^2 - 4x) x^2 - 4x = 0 x^2 - 4x + 4 = 0 + 4 (x - 2)^2 = 4 (x - 2)^2 - 4 -(x - 2)^2 + 4 4 - (x - 2)^2 | = integral sign | 1/(sqrt(4 - (x - 2)^2) dx u = ( x - 2) du = dx | 1/(sqrt(4 - u^2)) du = arcsin u/2 + C = arcsin (x - 2)/2 + C

**math**

n = the number n - 2 = subtract 2 from the number 2(n - 2) = double the difference 2(n - 2) + 7 = then add 7 2(n - 2) + 7 = 57 2n - 4 + 7 = 57 2n + 3 = 57 2n = 54 n = 27 The number is 27

**math--Unclear problem**

Your problem is not clear. 8 __ 72 __ 2 __ What does the ___ mean ?

**Algebra II**

2y - 1 = 3x - y/5 3x - 4/8 = y/4 First, simplify both equations 2y - 1 = 3x - y/5 Multiply both sides by 5 10y - 5 = 15x - y 11y - 15x = 5 3x - 4/8 = y/4 Multiply both sides by 8 24x - 4 = 2y -2y + 24x = 4 Multiply by 2 (11y - 15x = 5) Multiply by 11 (-2y + 24x = 4) 22y - 30x...

**Math**

Solve without graphing first so that you know what x and y equal. Then pick three points for each to graph. 3x + y = 6 x = 1, y = 3 x = 2, y = 0 x = 3, y = -3 2x + 3y = 13 x = 1, y = 11/3 = 3.67 (3.67 is a little more than 3 1/2) x = 2, y = 3 x = 3, y = 7/3 = 2.34 (2.34 is a ...

**Math**

I = PRT This is a formula for calculating simple interest. Interest = Principal * Rate * Time Example, you put $500 in a saving account, at 3% interest per year. To find the interest after two years, P = $500, R = 0.03, T = 2 I = 500 * 0.03 * 2 I = 1000 * 0.03 I = $30

**Algebra**

-3x + 2y = 8 x + 4y = -4 x + 4y = -4 x = -4 - 4y Substitute, x = -4 - 4y in, -3x + 2y = 8 -3(-4 - 4y) + 2y = 8 12 + 12y + 2y = 8 14y = -4 y = -4/14 y = -2/7 Substitute, y = -2/7 in either equation to find x. Then check your solutions in the original equations.

**Algebra 2**

R = 238.39x - 0.5x^2 x = 154 154^2 = 154 * 154 = 23716 R = 238.39(154) - -0.5(154)^2 R = 36,712.06 - 0.5(23716) R = 36,712.06 - 11,858.00 R = ?

**Math**

x = number of days to operate NJ y = number of days to operate OH z = number of days to operate GA 10x + 70y + 60z = 2150 (Handbags) 20x + 50y + 80z = 2300 (Shoes) 40x + 30y + 90z = 2500 (Belts) Solve for x, y, and z simultaneously If you want, post back with your answer and I...

**Math**

If your equation is, (5x - 2 + 3)/(x - 8) = 0 Multiply both sides by x - 8 5x + 1 = 0 5x = -1 x = -1/5

**math-No question**

What is your question?

**Math**

x = amt invested at 0.10 y = amt invested at 0.15 0.10x + 0.15y = 1440 x + y = 12000 Solve for x and y simultaneously If you are correct, x = $7,200 y = $4,800

**arithmetic**

(e²-2e+7)-(e²+2e+7) e² - 2e + 7 - e² - 2e -7 -4e^2

**Calculus**

v(t)= h(4t+h)/ h = 4t This should be, v(t)= 2h(2t + h)/h = 2(2t + h) = 4t + 2h v(t) = (2(t + h)^2 + 4 - (2t^2 + 4))/h v(t)=(2t^2 + 4ht + 2h^2 + 4 - 2t^2 - 4)/h v(t) = (4ht + 2h^2)/h v(t) = 2h(2t + h)/h v(t) = 2(2t + h) v(t) = 4t + 2h Then, lim h-->0 v(t) = 4t + 2h v(t) = 4t...

**math**

If you mean, y = 2x + 2, point (2,3) Parallel lines have the same slope. The slope-intercept equation form is, y = mx + b Slope = m and y-intercept = b y = 2x + 2 Slope m = 2 Therefore the parallel line has slope m = 2 y = 2x + b To find b, use the point (2,3). Substitute the ...

**College Algebra**

6 crates by 8 am 24 crates by 11 am Aver rate of change = change in crates packed/change in time Aver rate of change = (24 - 6)/(11 - 8) Aver rate of change = 18/3 = 6 crates/hr

**trig**

x^2 + y^2 = 49 r^2 = 49 r = 7 Arc length A = angle in rads * r To convert 30 deg to radians 30 deg * pi/180 = 30pi/180 = pi/6 A = pi/6 * 7 A = 7pi/6

**math**

x = amt invested at 0.07 y = amt invested at 0.12 0.07x + 0.12y = 215 x + y = 2000 Solve simultaneously for x and y

**math**

Area A = pi r^2 radius, r = 1/2 d pi = 3.14 1. d = 42, r = 1/2 d = 1/2 42 = 21 A = pi r^2 A = (3.14)(21^2) A = (3.14)(441) A = 1384.74 Do the 2nd problem the same as above.

**math please help**

First, reduce 6/4 6/4 = 3/2 For example, dividing 6 by 2/3 is the same as multiplying 6 by the reciprocal of 2/3. 6/(2/3) = 6 * 3/2 = 18/2 = 9 So, multiplying 6 by 3/2 is the same as dividing by 6 by the reciprocal of 3/2. 6 * 3/2 = 6/(2/3) = 18/2 = 9 Neither of your answers, ...

**algebra**

Amount spent, x, should be greater than or equal to $6,000 but less than or equal to $10,000. 6,000 <= x <= 10,000

**pre algebra**

10(-2x + 1) = 19(x + 1) Distribute the 10 and 19 -20x + 10 = 19x + 19 Combine terms -39x = 9 Solve for x x = - 9/39 = -3/13

**MATH**

Girls : Boys = 3 : 2 3x = girls 2x = boys 3x + 2x = 25 5x = 25 x = 5 Girls = 3x = 3(5) = 15 Boys = 2x = 2(5) = 10 How many more girls are there than boys?

**maths-Claire, please check problem**

ãx(8-x) ? Please edit your problem.

**math**

http://www.google.com/#hl=en&sugexp=ldymls&xhr=t&q=5000^5&cp=5&pf=p&sclient=psy&aq=0&aqi=&aql=&oq=5000^5&pbx=1&bav=on.1,or.&fp=5e2b21bd614e0a97

**Geometry-7th grade**

All sides of a Rhombus are congruent. Therefore, AB = BC = CD = AD BC = x + 9 DC = 5x - 2 BC = DC x + 9 = 5x - 2 4x = 11 x = ?

**Geometry**

This is an example of how this problem is done. Gilt?- none of the definitions I found had anything to do with measurement Draw a triangle ABC, side a = opposite side side b = adjacent side side c = hypotenuse You are given, side c = length of ramp = 14 side a = wheelchair ...

**Algebra 1**

Do you need to find L2? If two lines are perpendicular, the slope m of one is the negative reciprocal of the slope of the other, Slope m1 * m2 = -1 or, slope m2 = -1/m1 Your need to find slope m1 to write the equation of the perpendicular line. L1 = 3x - y = 2 To find slope m...

**algebra**

Are you Julie? This exact question was answered two days ago. http://www.jiskha.com/display.cgi?id=1298153937

**intermediate algebra**

x = amount invested at 0.05 y = amount invested at 0.03 0.05x + 0.03y = 28. x + y = 706 Solve the set of equations simultaneously If you are correct, x = $341 y = $365

**algebra**

All I could find was, 6 octillion, 789 septillion

**math**

Vanny, you are correct 6/20 = 0.3 or you can leave as 6/20 = 3/10

**calc**

Mistake fixed below -1/4 sin^3 x cos x + 3/4 (-1/2 sin x cos x + 1/2 | 1 dx ) -1/4 sin^3 x cos x + 3/4 (-1/2 sin x cos x + 1/2 x) + C -1/4 sin^3 x cos x - 3/8 sin x cos x + 3/8 x + C