Wednesday

October 1, 2014

October 1, 2014

Total # Posts: 10,750

**exponents**

#4 and #5 are both correct. For #8, it is x^8/y^8, since the question requires positive exponents. (You could have written it as x^8y^-8.) 1. 1/125 is 1/5^3. See if you can find the correct answer. 2. d^4*d^6 is d^10, so correction required. 3. the minus sign before the ...
*May 25, 2013*

**scientific notation am i doing it right?**

signature.
*May 25, 2013*

**scientific notation am i doing it right?**

Sorry, finger faster than the brain, forgot to change since last post.
*May 25, 2013*

**scientific notation am i doing it right?**

#1 is correct. The power of 10 refers to the number of positions the decimal point has to be moved, not the number of zeroes. So for #2, it should be 9.82000*100000=982000 Similarly, for #3, 9x10^3=9/1000=0.009 I will leave #4 for you to try.
*May 25, 2013*

**scientific notation am i doing it right?**

All correct, well done!
*May 25, 2013*

**Sequences**

Find the rule for number 2, which is a geometric series. You can tell if it is a geometric series by dividing any term by the previous. If the quotient is the same, then it is a geometric series. The rule for a geometric sequence is: t(n)=ar^n and r is the quotient by dividing...
*May 25, 2013*

**Sequences**

Let the nth term of the arithmetic sequence be t(n)=ax+b then t(1)=a(1)+b=7 t(2)=a(2)+b=12 Subtracting, we find 2a-a=12-7 which gives a=5 Substitute back into the formula, t(1)=5(1)+b=7, so b=2 the complete rule is then t(n)=5x+2 The nineteenth term is therefore t(19)=5*19+2=...
*May 25, 2013*

**polynomials am i doing it right?**

You're on the right track... 1. expand it and write it out when it is a subtraction: (x^4+7x^3+7)-(2x^4-4x^3+1) = x^4+7x^3+7) -2x^4+4x^3-1 = -x^4 + 11 x^3 + 6 2. space out your terms to avoid losing some of them. (3n^3 + n^2 -n -4)+(5n^3 -4n^2 + 11) = 3n^3 + n^2 -n -4 + 5n...
*May 25, 2013*

**How to get quick responses to your math questions**

Also, - DO check that the question you are about to post is complete and accurate before pressing the "post" button. - Do not omit parentheses. If the numerator or denominator of a fraction has more than one term, you need parentheses around them when you transcribe ...
*May 25, 2013*

**How to get quick responses to your math questions**

Math is a wide subject, ranging from K to 11, college and university. Then there is algebra, trigonometry, geometry, arithmetic, calculus, number theory, ... etc. Not all teachers answer all math questions (many do). If you would give a little more detail on which branch of ...
*May 25, 2013*

**Physics**

Hint: Find the resultant of the two given forces. The third force (which keeps the resultant in equilibrium) is a force which is equal in magnitude to the resultant, but opposite in direction.
*May 25, 2013*

**Maths**

Use the property of intersecting chords PA*PB=PC*PD In this case the chords intersect outside of Γ. Also, if T is the tangent to Γ passing through P, then PA*PB=PC*PD=PT²
*May 25, 2013*

**math**

Trade discount = $679.95*0.30
*May 25, 2013*

**trig**

So on the Cartesian plane, it is in the fourth quadrant, with x-y as (900,-500). Atan(-500/900)= -29° approximately. So the bearing is S61°E.
*May 25, 2013*

**Calculus**

Use substitution, p=sin(x), dp=cos(x)dx I=∫ydx =∫cos(x)(2sin(x)-1)^6dx =∫(2p-1)^6 dp Substitute again, u=2p-1, du=2dp I=∫u^6 (dp/2) =u^7/7 ÷2 + C Now back substitute u=2p-1=2sin(x)-1 I=(2sin(x)-1)^7 /14 +C
*May 25, 2013*

**Math/ Algebra**

Rewrite the equation in symmetric form x/a + y/b = 1 where a and b are the x- and y-intercepts respectively. y/2 -3x/5 = 1 can be rewritten as: x/(-5/3) + y/2 = 1 Identify the intercepts and graph accordingly.
*May 24, 2013*

**Math**

15/20/20 is a successive discount of 15%, followed by 20% on the discounted price, and finally another 20% of the doubly discounted price. For example, $1000 with a trade discount of 15/20/30 would have a final discounted price of $1000*(1-0.15)(1-0.20)(1-0.30)=$476 So the ...
*May 24, 2013*

**Math/ Algebra**

See http://www.jiskha.com/display.cgi?id=1369451313
*May 24, 2013*

**Math**

p=probability of scoring (success) = 0.8 q=probability of not scoring (failure = 0.2 Assuming the probability does not change over time and is independent of previous results, then we can apply the binomial distribution: P(7+ out of 8) =8C7*0.8^70.2+8C80.8^8 =0.34+.17 =0.50 (...
*May 24, 2013*

**statistics**

Ah! I see it now. "y (in tens of thousands of dollars)" That might be the culprit.
*May 24, 2013*

**statistics**

Did you put $5.13 or 5.13?
*May 24, 2013*

**Statistics**

There are different ways to find the regression line. Do you know which one you are supposed to use? It should be around y=-0.6x+310. Try to calculate the coefficients and we can check you answer. Do specify the method, and work details if you can.
*May 24, 2013*

**statistics**

If you are working on the computer, you have to get the answer exactly right. It asked for the answer to 2 decimal places. If you put three (3.625), it could mark you wrong. On the other hand, there are two ways to round it to 2 decimal places. Most people round it up when it ...
*May 24, 2013*

**Math - please help**

The height is 280 ft. Distance from apex to mid-point of base = 356.1 ft = slant height. Area of one side = (1/2)base*slant-height then choose the correct answer.
*May 24, 2013*

**Calculus**

Let f(x)=sqrt(1+6x) then f'(x)=3/sqrt(6*x+1) and f'(0)=3 Thus the slope of the curve is 3 at x=0. f(0)=1 means that the tangent to the curve passes through (0,1)=(x0,y0). So the linearization is y=Ax+B =Slope(x-x0)+y0 =3(x-0)+1 =3x+1 Identify A and B for your answer.
*May 24, 2013*

**Maths**

For x near 1, you can use linearlization, which is f(x)=f'(1)(x-1)+f(1) =(1/8)x+f(1) Therefore, within the errors of the linearization, f(x)-f(1) = (x-1)/8 (approximately)
*May 24, 2013*

**geometry - missing information**

To scale or not, we don't get to see it. So we depend on you to describe the figure.
*May 24, 2013*

**please answer simple stat any tutor**

Think of the test as μ1>μ2 Is the solution of μ1 on the left, right or both sides of μ2?
*May 23, 2013*

**algebra**

slope of line y=(2/5)x+7 is (2/5) Slope of line perpendicular to it is -(1/slope)=-5/2.
*May 22, 2013*

**Frenchhhhhhhhhh**

All the cases are direct objects, so you need to replace them by le/la or les (not "des")depending on whether the nouns you are replacing are in singular or plural, and masculine or feminine. There is an extra caution in French is that the pronouns of direct objects ...
*May 22, 2013*

**Frenchhhhhhhhhh**

Replace by what?
*May 22, 2013*

**Algebra - clarifications required**

y=2x=1 is not an equation of a line. Please clarify the typo.
*May 21, 2013*

**Algebra - clarifications required**

1. slope = 15/12 2. slope = -5/4 3. slope = ? (two equal signs, so the sign of the slop could go either way. Please clarify.
*May 21, 2013*

**pre calc**

If sin(x)=-3/5 in Q3, then cos(x)=-4/5 (using cos²(x)=1-sin²(x)) Similarly, cos(y)=5/13 in Q1 means sin(y)=12/13 sin(x-y)=sin(x)cos(y)-cos(x)sin(y) =-3/5*5/13 - (-4/5)*12/13 =(-15+48)/65 =33/65
*May 21, 2013*

**Math**

Yes, it's correct. 2 gals must be added (and well agitated).
*May 21, 2013*

**Math (Probability)**

The size of the sample space of the last throw is 20*20=400. Out of the 400 outcomes, Bret needs those where his throw is 11 or more than Shawn's, namely: (12,1),(13,1),(14,1)...(20,1) (13,2),(14,2)...(20,2) ... (19,8),(20,8) (20,9) There are ∑(i), i=1,9 outcomes. Can ...
*May 21, 2013*

**math**

One cup is 240 ml 1 table-spoon is 15 ml. So 1 cup = 16 table-spoons How table-spoons are in 16 gals? This equals how many cups?
*May 20, 2013*

**Math**

Certainly, if the father has a foot-length equal to 150% of that of Aaron.
*May 20, 2013*

**Physics**

Use the definition of a Coulomb. There are 11 ampères of current 10 minutes = 600 seconds. Can you now figure it out?
*May 20, 2013*

**math**

Let E=age of Mr. Edwards. (E+15 + E/3+15) = 86 Solve for E.
*May 20, 2013*

**Pre-Calculus**

Draw a right triangle with XY vertical, and a base AX of 200 ft. The angle XAY=25 degrees. Use the definition of tangent(A)=tangent(25°)=XY/AX Solve for XY.
*May 20, 2013*

**7th Grade Math**

Volumes are (linear ratio)³ and areas are (linear ratio)²
*May 20, 2013*

**probability**

There were 40 outcomes, of which 6 were spinning a 2. Experimental probability = 6/40 = 3/20.
*May 20, 2013*

**7th grade math help :)**

You're welcome!
*May 20, 2013*

**7th grade math help**

Assuming one must make a single choice in each group, so it is a three-step experiment. choices for group 1 = 2 choices for group 2 = 3 choices for group 3 = 2 Total number of outcomes in the sample space is therefore the product of the choices in each group (step).
*May 20, 2013*

**physics**

v0=5.5 m/s v1=0 m/s F=160 N m=80 kg Use Newton's second law, F=ma a=F/m=-2 m/s-2 (deceleration) Use: (v1^2-v0^2)=2aS So S=(v1^2-v0^2)/2a=30.25/4=7.5625 m
*May 20, 2013*

**Physics**

F=>M2=>F1=>M1 On the frictionless table, both will have an acceleration a. Draw the free-body-diagrams (FBD) and conclude that M2.a = (F-F1) M1.a = F1 using Newton's second law. Solve for F1 and a. Part (b) can be found in a similar way.
*May 20, 2013*

**calculus**

Steve is right. Whenever you transpose a fraction from a book to a single line to post, you need to insert the implicit parentheses. In this case, I believe it is 1000 = 10,000(1 − (5/[5 + e^−0.001x]))
*May 20, 2013*

**calculus**

p = 10,000(1 − (5/5 + e^−0.001x)) for p=1000, 1000=10000(1 − (5/5 + e^−0.001x)) 5/(5+e^(-0.001x)=0.9 e^(-0.001x)=5/0.9-5 take log -0.001x = log(5/0.9-5) x=-1000 log(5/0.9-5) =587.8, say 588 (b) can be done in a similar way.
*May 20, 2013*

**Math 208**

Let x be the amount he invested at 6%. Then x-1400 is the amount he invested at 5%. Total interest after 1 year x*0.06+(x-1400)*0.05=172 0.11x=172+1400*0.05 0.11x=242 x=2200 Check 2200*0.06+800*0.05=132+40=172 ok.
*May 20, 2013*

**programming - C++ or Java?**

The instructions are quite clear as to what to do. I suggest you read through your teacher's notes or instructions and give an attempt. Programming is learned by actually writing and compiling code. Copying or reading alone will not help you solve your next problem. You&#...
*May 20, 2013*

**Physics**

Speed of sound in sea water depends on the temperature and salinity. At 25 degrees and 35 ppt salinity, the speed of sound is approximately 1551 m/s. So divide 19000/1551 to give the time in seconds it takes.
*May 20, 2013*

**Math**

Basically you cannot. A bar graph puts different numbers into the same class, and so there is loss of information. If you have a problem in hand, post the data (if they are not too numerous) and we can appreciate better the problem in hand.
*May 20, 2013*

**Calculus**

Parentheses are implicit when it is printed in fraction form. If it is printed as a fraction, your post is linearizing it (put on a single line) and it is necessary to insert parentheses around all numerators or denominators which contain more than one term.
*May 20, 2013*

**Calculus - clarifications required**

Could you please insert parentheses to clarify the question? 10x-3/5x+6x could mean (10x-3)/(5x+6x) [??] 10x -(3/5x) + 6x [??] [(10x-3)/5x] +6x [??} etc.
*May 20, 2013*

**Algebra - clarifications required**

Jamila, please clarify what SR stands for. Is it a monetary unit, or is it an abbreviation for some term?
*May 20, 2013*

**calculus**

Find derivative with respect to x: y'(x)=dy/dx=6x-5 Evaluate derivative at x=3: y'(3)=6(3)-5=13
*May 20, 2013*

**Algebra**

Using calculus, it would be finding dy/dt and equating to zero to solve for t. Since it is algebra, you could complete squares: y=-4.9(t-7)²+49*4.9 =-4.9(t-7)²+240.1 which means that the maximum height of 240.1 m at t=7.
*May 20, 2013*

**math**

You can take the average, namely [(1+2)/8]2 = 3/16 If you want just ANY fraction between, you can add the numberators and denominators: (1+1)/(8+4)=2/12 = 1/6
*May 20, 2013*

**Computer Science**

Depending on the complexity of the game, it takes proficiency in the language, which means lots of late nights leaning and practising programming on different projects. In short, you have to like it so that it is not work, but fun.
*May 20, 2013*

**please hurry**

It is almost impossible to show the calculations here because the proportional font used here makes it difficult to line up calculations. You can look up an example at the following link: http://www.homeschoolmath.net/teaching/square-root-algorithm.php
*May 20, 2013*

**maths-formula**

Sorry mate, this expression does not have rational factors.
*May 20, 2013*

**Physics**

Since it is an elastic impact, we can equate energies.
*May 20, 2013*

**Probability**

Only question left is how Andrew found a fair 10 sided die. Platonic solids have 4,6,8,12 and 20 sides!
*May 20, 2013*

**Probability**

Use a probability tree to find that the overall probability of winning is [∑(i²)/100]/10] for i=1 to 10 =385/1000 which should be simplified to an irreduceable fraction a/b. The sum of a+b is then 277.
*May 20, 2013*

**maths**

Subdividing a pizza according to the number of people, getting change after paying for a purchase, finding unit price of items in a grocery store to compare unit cost, checking that the restaurant bill is correct, calculating tip, counting money after a withdrawal, finding the...
*May 20, 2013*

**Algebra**

See http://www.jiskha.com/display.cgi?id=1369047938
*May 19, 2013*

**Algebra**

See http://www.jiskha.com/display.cgi?id=1369047938
*May 19, 2013*

**French-SraJMcGin**

Watch spellings of "Sacré-Coeur", as pointed out by Mme Sra. The proper name seems to be "La Basilique du Sacré Coeur"
*May 19, 2013*

**math**

This equation is separable, so dy/dx = 6xy dy/y = 6xdx Integrate both sides, log(y)=3x²+C1 y=Ce3x² y(0)=40 -> C=40 therefore y=40e3x²
*May 19, 2013*

**geometry**

Draw a rhombus, and mark one side as 24 cm, and one of the diagonals as 24 cm long. Then the half diagonal is 12 cm. Since the diagonals of a rhombus intersect at right angles, we have a right-triangle with hypotenuse 14 cm, with one side as 12. The other half-diagonal is ...
*May 19, 2013*

**Geometry - incomplete?**

You are probably missing a diagram or figure. x has not been mentioned in more than one place in the question.
*May 19, 2013*

**advanced algedra 2**

Substitute y=x² a) y²-9y+18 =(y-6)(y-3) and put back y=x².
*May 19, 2013*

**Mathematics**

θ=133 rpm = 133*2*π/60 radians/s Speed = rθ=40/100 m *θ =1.7733π m/s =5.571 m/s (approx.)
*May 19, 2013*

**math please hurry**

Assuming the code uses English alphabet, Choices for first letter: 26 Choices for second letter: 26 Choices for third letter: 26 Choices for digit: 10 Total number of codes = product of all 4 choices.
*May 19, 2013*

**Algebra**

Since the title is "algebra", I assume calculus cannot be used. In this case, complete squares of P(x). P=-5(x-20)²+2200 which means that P(x) is at a maximum when x=20, and P(x)=2200.
*May 19, 2013*

**advanced algedra 2**

See: http://www.jiskha.com/display.cgi?id=1368991756
*May 19, 2013*

**Geometry**

Lateral surface area of a cone Al = πrL r=radius of base L=slant height. So Area of canvas = π(12.5)(26)
*May 19, 2013*

**To GANDU MAN**

Your geometry problem of yesterday has been answered. http://www.jiskha.com/display.cgi?id=1368886945
*May 19, 2013*

**math**

a^3=1/cos-cos = (1-cos^2)/cos=sin^2/cos b^3=1/sin-sin = (1-sin^2)/sin=cos^2/sin a^3/b^3=sin^2/cos * cos^2/sin=sin^3/cos^3 => a/b=sin/cos = tan (Hope you understand your own notations.)
*May 19, 2013*

**statistics**

μ=98.2 σ=0.62 Z(100)=(100-98.2)/0.62=2.903 Look up (normal) probabilities for Z=2.903 from tables (for people with temperatures below 100). Subtract from 1 to get probabilities of healthy person considered having a fever.
*May 19, 2013*

**Mathematics**

Assuming radiator reaches 120° between 0 and 4 minutes. Trying to solve: 120 = 6.2t² + 12t +32 or 6.2t² + 12t - 88 = 0 Use quadratic formula to get t=-4.8 or t=2.92 sec. Reject t=-4.8 because it is not within interval [0,4].
*May 19, 2013*

**Algebra**

1. The transformations are: e(O,2) : dilation about origin of 2 units t(0,5) : translation 5 units up r(y,-x) : rotation counter-clockwise 90° So (x,y)-> (2x,2y) -> (2x, 2y+5) -> (2y+5, -2x) So combining it all: (x,y) -> (2y+5, -2x) 2. Using Cramer's rule...
*May 19, 2013*

**Physics**

We are unable to help you solve the problem without guessing how the objects are configured. You can describe in detail how the objects are arranged, or post the diagram at an external site and post the link.
*May 18, 2013*

**Math 4 questions**

"at most" means ≤ "minimuum of" means ≥ "less than" means < "low of" means ≥ "high of" means ≤ You will be more likely to get an answer quickly if you show your attempts.
*May 18, 2013*

**Algebra II Part 2**

Thanks Steve, good thought!
*May 18, 2013*

**Algebra II Part 2**

use the identities: tan(x)=sin(x)/cos(x) cot(x)=cos(x)/sin(x) and sin(π/2)=1, cos(π/2)=0 sin(0)=0, cos(0)=1
*May 18, 2013*

**ALGEBRA**

Use compound interest formula: Amount = Principal * (rate)^n rate=interest rate per period n=number of periods compounded. Here rate = 1+ 0.07/2=1.035 number of periods = 3 years * 2 periods/yr principal=$7300 The question didn't say what's required.
*May 18, 2013*

**Exponential modelling**

Let the mathematical model be f(x)=ax^b where x=years past 1970. f(x)=population in millions Note: much better accuracy is obtained by shifting the origin to 1970, the closest possible. Substituting given data for 1970: 5.1=ax^0=a so f(x)=5.1x^b For 2004, 14.3=5.1(34^(b)) or ...
*May 18, 2013*

**geometry**

Area of annulus (area between circles of radii a and b) = π(a+b)(a-b)
*May 18, 2013*

**geomerty**

There are different ways to solve for the circumscribed radius, depending on which part of geometry you are working on. The most basic calculation taking advantage that the triangle ABC is equilateral is to construct a perpendicular bisector on side BC such that ABD is a right...
*May 18, 2013*

**Trigonometry**

If sin(α)>0, then 0<α<π. So α1 = asin(15/17)=1.0808 radians and α2 = π-α1.
*May 18, 2013*

**French**

While you're waiting for Mme Sra, you could make a review on the following: - If you abbreviate the church, you need to know what the omitted word (Basilique) is masculin or feminine. If you mean the official name of La Basilique du Sacré Coeur, then you should ...
*May 18, 2013*

**Algebra**

Use the fact that the sum of the interior angles of a triangle is 180°. So x+(2x+24)+3x+48)=180. Solve for x.
*May 18, 2013*

**Multiplication**

"what is 1250* 2987" Let's do this mentally: 1250*2987 =29870000*0.125 =29870000/8 = 3733750
*May 18, 2013*

**math**

Note: Segment lengths BA and AB assumed to be equivalent in the following proof. BN/sin(BAN)=BA/sin(BNA) (sine rule) => BA/BN=sin(BNA)/sin(45) AC/sin(CNA)=NC/sin(45) (sine rule) => AC/NC=sin(CNA)/sin(45) Since sin(BNA)=sin(180-BNA)=sin(CNA) BA/BN=AC/NC, or CN/NB =AC/AB=...
*May 18, 2013*

**mathematics**

Use the standard form of a linear equation: y=m(x-h)+k where m=slope=-3 (h,k)=a point through which the line passes (9,7)
*May 7, 2013*

**algebra**

Conventional algebra: x=number of small cups y=number of large cups form the system of equations x+y=155 2x+3y=335 Solve the system for x and y. Quick way by substituting directly: Let 155-x=number of large cups 2x+3(155-x)=335 Solve the linear equation for x. Faster way by ...
*May 7, 2013*

**Statistics**

Use binomial probability because: probability is known and does not change over the experiment, outcome is binomial (success or failure), each step of the experiment is similar, p=0.25 n=10 P(r)=number of question correct =nCr(p^r)(1-p)^(n-r) nCr = binomial coefficient = n!/((...
*May 7, 2013*

**algebra 2**

g(x) = 4x^4 + 4x^3 - 11x^2 -12x -3 =x²(4x²+4x+1)-3(4x²+4x+1) =(x²-3)(4x²+4x+1) =(x+√3)(x-√3)(2x+1)² => g(x)=0 has roots ±√3,-1/2 (twice)
*April 16, 2013*

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