Posts by Reiny
Total # Posts: 40,469

Math check my answers please!!!!
1. volume = (1/3)(base)(height) = (1/3)(81)(4) = 108 , you are wrong 2. correct 3. correct 
Math
The prob(7 with 2 dice) = 1/6 , a trivial question by itself so of 1000 tosses, how many would total 7 ?? 
math
are the tickets returned, so that the same ticket could win more than once? 
Calculus
I told you what to do in https://www.jiskha.com/display.cgi?id=1524618205 btw, in Damon's formula he forgot the square of the radius 
Calculus
Show me what you have done so far. a) The first part especially should be very straightforward. you should get 4/9 for the 2nd part, let the new vertical be x = h, so you have 2? (1/x^3) dx from 1 to h = ?(1/x^3) dx from 1 to 3 , the last part you found in part a) c) remember... 
math
let D/2 = x, and d/2 = y , where D > d make a sketch, draw in the common tangent, join OP, and draw a line parallel to the tangent from P. I see a rectangle and a rightangled triangle. The hypotenuse H of the rightangled triangle is equal to the length of the common ... 
math
the rotation matrix is ?cos45 sin45? ?sin45 cos45 ? ??2/2  ?2/2? =??2/2 ?2/2? multiply this by ?x? ?y? gave me x' = ?2/2 x  ?2/2 y y' = ?2/2 x + ?2/2 y subbing that into xy=9 (?2/2 x  ?2/2 y)(?2/2 x + ?2/2 y) = 9 2x^2/4  2y^2/4 = 9 x^2  y^2 = 18 
Geometry
No, for both The slopes of perpendicular lines are negative reciprocals of each other. that is, you have to change the sign and flip the fraction for your first one: slope of 2 turns into a slope of +1/2 for the second the slope of +5 turns into 1/5 (a slope of 3/4 would ... 
math
start with general point (x,y) reflection in the xaxis > (x, y) then a reflection in the yaxis >(x,y) reflection in the origin: (x,y) > (x,y) Yup, Julie is correct. 
Math
Choose 1 fruit from 7, and 1 juice from 2 that is C(7,1)*C(2,1) = 14 assuming the order of putting in the fruit and the juice in the smoothie doesn't matter since you are blending it anyway. 
math
Your description is not clear. At first I read it as a cylinder sitting on top of a cube. Then you talk about a circular shape on the top. I can't visualize it Are there two questions here ? 
Maths
based on the fact that if you have ax^2 + bx + c = 0, the sum of the roots = b/a and the product of the roots = c/a often this is a avery efficient way to proceed, especially if the roots are irrational or complex. Unfortunately, this does not appear to be on the curriculum ... 
Maths
f(z) = z^3  2z + 4 , note how we type exponents all complex roots , and irrational roots, come in conjugate pairs, so the roots are 1+i and 1i sum of those is 2, product of those is also 2, so the quadratic producing those is (z^2  2z + 2) by long division that gives: (z+2... 
Algebra
Your first question probably was: Where do the graphs of these equations intersect the xaxis ? the answers you gave are correct 
Finance Math
amount = 2990  2990(.7)(.88)(.95) 
Math
true only if A and B are complementary angles e.g. cos 20° = sin 70° 
Math
term(n) = n(n2)3 term(1) = 1(12)  3 = 1(1)  3 = 4 term(2) = 2(22)  3 = 2(0)  3 = 3 continue 
Math
without graphing I notice that (1,2) and (1,7) lie on a vertical line, and (1,2) and (4,2) lie in a horizontal line. so .... 
Math
If the given information is that x1 is a factor then f(1) = 0 > p = 7 A synthetic division by x1 yields a quotient of (3x^3 + 5x^2  x 7) but another division by x1 yields a quotient of (3x^2 + 8x +7) so 3x^4+2x^36x^26x+p=0 > (x1)(x1)(3x^2 + 8x + 7) if p... 
Math
cost1 = 10 + 4g vs cost2 = 6 + 6g Your "task" is to simply solve 6+6g = 10+4g to get the breakeven point. Just graph the two equations as if they were y = 4x + 10 and y = 6x + 6 to illustrate. http://www.wolframalpha.com/input/?i=plot+y+%3D+4x+%2B+10,+y+%3D+6x+%2B+6... 
Math
Did you substitute the given points in the inequation ? That's how you can tell. e.g. first one: (3,4) is 4 ? 125 ??? 
Math
I agree with your first part, but not the second get a "feel" for the numbers, e.g. let x = 1000 then f(1000) = 1001/999 = appr 1.002 let x = 1,000,000 then f(1000000) = 1000001/999999 = 1.000002.. if you take large negative values you will get appr .9999... So don&#... 
math
It is good to have the quadratic in factored form but useful only if the product is zero. In your case it is 7, so that is useless. Expand and recalculate the constant .... 2x^2  6x + 3x  9 = 7 2x^2  3x  16 =0 hint: it does not factor , so you have to use the quadratic ... 
math
Unless you make an error in the "switching" 0=8+4tt^2 > t^2  4t  8 = 0 hint: use the formula, or complete the square 
Math
Place your ellipse into standard position, a = 50, b = 10 for such as ellipse: c^2 + b^2 = a^2 find c, the distance between 2 foci would be 2c 
Advanced Algebra
find the present value of an annuity of $4900, with n = 120 and i = .029/12 then it is obvious which is the better deal. btw, I did not get any of the answers given. How did you get d ? 
Math
You must be studying parabolas to have this type of question. You must have learned how to find the vertex of a parabola find the vertex (t, h) the t is the time when you reach the maximum height the h is the maximum height obtained. as to the height of the building, let t = 0 
math
1/8x^2=x5/2 multiply each term by 8 x^2 = 8x  20 x^2  8x + 20 = 0 You MUST know how to do the rest 
Algebra
geesh, all they did was change the numbers. here is a start: small stamps  s large stamps  l s+l = 7 ** 20s + 30l = 180 > 2s + 3l = 18 *** solve the two equations ** and *** or small ones  s larger ones  7s 20s+30(7s) = 180 solve for s, then 7s 
Algebra
answered here: https://www.jiskha.com/display.cgi?id=1198461333 
Algebra
original fraction  (x4)/x new fraction: (x14 + 17)/(x + 17) = 5/6 solve for x, then form your fraction 
maths
well, 300,000,000 m/s = 300,00 km/s just the 99.33 million km by 300,000 km/s that will be your answer is seconds, divide by 60 to get minutes, multiply the decimal part ONLY of your answer by 60 to get the seconds 
maths
"You will enter minutes in part I and seconds in part II" How do you expect us to enter the values into your online webpage ? 
Math
Hard to tell 
LA
https://www.google.ca/search?q=walk+two+moons&rlz=1C5CHFA_enCA690CA690&oq=walk+two+moons&aqs=chrome..69i57j0l5.5299j0j8&sourceid=chrome&ie=UTF8 I got 1,700,000 hits 
Finance Math
let the total be x "...represented 23 less than 1/5 of the total " > (1/5)x  23 What is that "equal" to ?? 
Finance Math
profit on muffins  x profit on donuts  4.5x what do you know about these profits? 
math
How did you possible get that ? I gave you the answer, all you had to do is reduce the fraction to lowest terms. 
math
prob(not win) = 219/264) prob(win) = 1  219/264 = ... 
Math
by definition, n! = 1x2x3x...xn e.g 4! = 1x2x3x4 = 24 
Math
Your calculation makes no sense, so yes, you are totally wrong. In the wording of the question I linked to, it said "How many consecutive free throws must he miss" , yours does not say that. The way yours is worded, there could be shots that he made and shots that he... 
Math
same question here, with slightly different wording https://www.jiskha.com/display.cgi?id=1524063058 
Algebra
You must solve the 2 equations to find their intersection. just add them the way they sit: x+y = 4 xy = 2 ........... 2x = 6 x = 3 sub that back into either one: > y = 1 so they intersect at (3,1) for your 2nd , any straight line going through the origin can't have... 
Algebra
solve for x, the number of hits (10+0)/(16+x) = 4/10 
Math
just use your rules of exponents a^x ÷ a^y = a^(xy) you have the same base of (?2÷5) 
Algebra
Notice that (2a + 6b) is a common factor, so ... (2a+6b)( (6b2a)  (2a+6b) ) simplify the inside of my outside brackets and you are done 
Algebra
numerator  x denominator  x+1 fraction = x/(x+1) if (x1)/(x+1) = 3/4 4x  4 = 3x + 3 x = 7 original fraction = 7/8 check: 6/8 = 3/4, my answer is correct 
Math
for two points, (x1,y1) and (x2,y2) the slope = (y2y1)/(x2x1) apply it to your two points, show me your work 
math
Try the point in each equation. a. 1  35 = 4 ? NO b. 1 = 710 ? NO c. 1 = 28 + 3 ? NO d. 1 = 7 + 8 ? YES where you just guessing ?? 
math
A google search about slope would give you thousands of results, but your first source would be your text or notes 
math
I disagree a. 5 = 75+10 ?? b. 0 = 10+10 ?? c. 5 = 5+10 ?? d. 25 = 15+10 ?? 
math
correc 
math
Did you mean y =  x ? , namely the absolute value? in that case , all results of x would be positive, and x would be negative. ordered pairs would be 3 3 2 2 1 1 0 0 1 1 2 2 3 3 plot them, remember you can't connect them with a straight line, since you are... 
Math (please help me)
From 10 going 3 units to the right puts you at 7 from 6 moving 12 units down puts you at 6 so ...... 
algebra
looks like her marks are going up 5 per test. so ... 58 63 68 73 ...... count to decide when you go over 85 
math
multiply the 2nd by 10 1010x  10y = 1110 add to the first 1010x  10y = 1110 11x + 10y = 1100 ............................... 1101x = 11010 x = 10 in the 1st 110 +10y = 1100 10y = 1100110 = 110 y = 11 
Finance Math
This is very similar to the other two questions I have answered for you. You did not respond to either one, so can I know if you understand this type ? Surely you don't expect me to just do these for, do you ? 
Finance Math
What does the credit rating have to do with the calculations of the problem ? Anyway.... What "they" probably want you to do is find the payment in each case (see my previous solution), multiply each by 360, then subtract the original home value from each one. 
Finance Math
I will assume the compounding is monthly to match the payment period, or else we have a messy solution i = .07/12 = .00583333... n = 360 paym(1  1.0058333..^360)/.00583333... = .8(50000000) 
Finance Math
i = .06/12 = .005 n = 12*30 = 360 pmt = ?? pmt( 1  1.005^360)/.005 = 500000 pmt = 2997.75 the interest in the first month = .005(500000) = 2500 so the actual reduction in the principal for the 1st month = 2997.752500 = 497.75 leaving a balance of $499,502.24 
Math
10.5 miles > .9 inches 1 mile > .9/10.5 inches then 36.2 miles > 36.2(.9/10.5) inches start crunching the numbers 
Algebra
I will do one of the values, you do the rest x = 2 y = 2 =  2 by the way, all your y values will be negative 
math
V=?r^2h r^2 = V/(?h) r = sqrt( V/(?h) ) 
math
.0144L = 5.000 solve for L 
Mathplease check
I agree 
Maths
Agreeing with bobpursley and trying to make sense of your atrocious spelling, 4rm > from ??, d > the ???? you probably want: y/10 = cos50 y = 10cos50 = .... 
MATH
I don't I see two variables but only one equation. Who is supposed to be .0191 ? 
math
You only have 3 choices: equilateral: all sides would have to be equal. Are they? isoscelse: two of the sides would have to be equal. Are they? scalene: all sides are different. Are they? All you had to know was the names of these terms. 
Math degrees
Jeffrey meant to say: 360/9 = 40 
Algebra
If the coefficients are reasonably small, I will look for factors first. e.g. 2x^2  11x  6 You know the factors can only be (2x ....)(x ....) for the front and for the back in can only be (.... +2)(... 3), (.... 2)(.... +3), (.... +6)(..... 1), (.... 6)(..... +1) With a ... 
Probability
Still waiting for your answer choices, so we can check them Meantime, make sure you know the distinction between "probability" and "odds" I will do #5 for you to show that difference 5. MONTANA > 3 vowels out of 7 letters Prob(picking a vowel... 
Math
I don't see a single answer supplied by you. How can we check your work. You don't for a minute expect somebody to actually do this test for you? 
Math
So if the width = 3x+1 what is twice that ? recall that area = length x width, so ..... 
Algebra
Time to complete the first trip  t hrs time to complete the return trip = (t  1/2) hrs distance of first trip = rate x time = 48t miles distance of return trip = 60(t1/2) miles aren't the two distances the same ?? 
Mathh
width x length  x+3 x^ + (x+3)^2 = 15^2 solve for x, reject the negative answer for x 
math
Number of possible passwords = 26*10*10 = 2600 so p = 1/2600 not p = 1  p 
math
go with Steve's multiplication I picked the "wrong" special symbol, should just stick with standard keyboard keys 
math
can you not find 1.8×10^4 ÷ (3.6×10^?2) ? hint: remember your exponent laws 
Algebra
surely you can simplify 9x^3+2x^25x+4  (5x^37x+4) Hint: there will be a common factor of 2x The other quadratic multiplier does not factor 
Mathh
Let 5t2 + 20t + 0.8 > 15 5t^2  20t + 14.2 < 0 You know that y = 5t^2  20t + 14.2 is a parabola opening upwards find the roots of 5t^2  20t + 14.2 = 0 , and the time will be the time between those two roots 
Math
area of base of bale = 2(3) ft^2 = area of circle = ?(1.5)^2 evaluate then decide which has the bigger area since both have the same height > the larger area will yield the larger volume 
Finance Math
Using this weird method, monthly payment = (700 + 700(.09)(1)/12 = 763/12 = 63.58 let the real monthly rate be x 63.58(1  (1+x)^12)/x = 700 this type of equation is very messy to solve, so let's go to Wolfram https://www.wolframalpha.com/input/?i=solve+63.58(1++(1%2Bx)%... 
MATH APR of a loan
Ms Sue has 2 typos in that she used 6 years instead of 5, and 242.81*60 = 14568.86 Her rate would have been R = 2568.60/(12000*5) = .043 or appr 4.3% Using compound interest, since the time > 1 year let the real monthly rate be x 242.81(1  (1+x)^60)/x = 12000 1  (1+x)^... 
Math
cuberoot(3) = 1.44225... don't round off at this point so 5*cuberoot(3) = 5(1.44225) = 7.211247.... , not 7 now that is the value of x, so x^3 = (7.211247....)^3 = 374.9999919.... , close enough for 375 for you? your appromation of 7 would give us 7^3 = 343, off quite a bit 
Math
x^3 = 375 so you need the simplified cube root of 375 hint 375 = 125*3 what is special about 125 ? 
Financial math
yes 
Financial math
first step is to find the quarterly payment. Did you do that ? 
Algebra
You got it, and to top it off, since 169 is a perfect square they are even rational (still real though) 
Algebra
well, both can't be true, can they ? Hint, have you calculated the discriminant ? 
Finance Math
Make a time graph, marking 'now', yr1, yr2, .... yr7 place x at now, yr1, yr2, yr3, 7500 at each of yr4, yr5, yr6, and yr7 Pick the end of yr3 as your focal point At that point in time , the Amount of the deposits = Present Value of withdrawals x( 1.036^4  1)/.036 = ... 
math
No I suggest making a quick sketch of y = 3sinx and y = 3sin(2x) + 1 pick critical angles like 30, 45, 60, 90 degrees etc 
Math/Algebra
yes 
Math/Algebra
nope, did you use x = 2.5 ?? 
Math
x^2 + 6x = 5 x^2 + 6x + 5 = 0 (x+1)(x+5) = 0 x=1,x=5 written as a set, {1,5} What part confuses you? 
math
If I understand you correctly, DF is the diameter of a halfcircle radius is clearly 4 units, so that part = ?(4^2) = 16? units^2 slope EF = +1, slope DE = 1, so obviously you have a rightangled triangle Find the length o EF and DE and use the area of a triangle formula to ... 
math
did you plot the points ??? https://www.wolframalpha.com/input/?i=plot+(1,8),+(3,5),+(4,0),+(3,0),+(3,5),+(1,8) looks like by joining (3,5) and (3,5), I now have a trapezoid, (easy to figure out) and a triangel with a horizontal base and countable height. let me know what... 
Geometry
V = (1/3)?r^2 h so if you just double the height, the volume is doubled if you double the radius, the volume will be quadrupled r^2 > (2r)^2 = 4r^2 if you double both height AND radius, the volume would increase by a factor of 8 r^2 h > (2r)^2 (2h) = 8r^2 h 
Finance Math
Waiting for you to show your work or your area of difficulty. Clearly nobody is just going to do your work for you. 
Math
Your link did not work, but I think you are attempting to write a continued repeating fraction. Here is a link to introduce you to the topic of continued fractions http://www.maths.surrey.ac.uk/hostedsites/R.Knott/Fibonacci/cfINTRO.html#section1.5 it is clear that its value &... 
Algebra
For ax^2 + bx + c = 0 the sum of the roots = b/a the product of the roots = c/a so for 3x^2  5x  2 = 0 the sum of the roots = .... the product of the roots = ....