Wednesday

July 30, 2014

July 30, 2014

Total # Posts: 24,029

**College Algebra**

x^2-9x-1 = 0 x^2-9x = 1 x^2 - 9x + 81/4 = 1 + 81/4 (x - 9/2)^2 = 85/4 x - 9/2 = ±√85/2 x = 9/2 ±√85/2 = 1/2 (9±√85) 2x^2+17x+2 = 0 2x^2+17x = -2 2(x^2+17/2 x) = -1 x^2 + 17/2 + 289/16 = -1 + 289/16 (x + 17/4)^2 = 273/16 x + 17/4 = ±...

**Algebra 1**

(x+a)(x+b) = x^2 + (a+b)x + ab If a>0 and b<0, then ab<0 so there's no way that n can be positive if a and b have different signs.

**Simplify Polynomials**

18x^2+6+4x-15x^2-4+13x (18-15)x^2 + (4+13)x + (6-4) 3x^2 + 17x + 2 3x^2+6-2x+5x-4x^2+9 (3-4)x^2 + (-2+5)x + (6+9) -x^2 + 3x + 15 3x^2+3x-7x+3-5x^+2 (3-5)x^2 + (3-7)x + (3+2) -2x^2 - 4x + 5 -5 is the coefficient of x -4 is the coefficient of x^2 (m^2-m-4)+(m-5) m^2 + (-1+1)m + ...

**Algebra Math**

the 3 movies use 3.6+2.8+4.1 = 10.5 GB So, his available space will be 8.25+2.3 = 10.55 GB

**algebra math**

9pts/6wks = 3/2 pts/wk

**check set up trigonometry**

Nope. cot28 = x/360

**Math**

Hmmm. I don't see an obvious application of the law of sines here. However, if we consider the distance directly to the plane, and call the first one x and the second one y, then 1000/x = sin52° 1000/y = sin16° Then we want the distance z given by the law of cosine...

**check my set up please, trig**

(105-5)/x = sin43°

**algebra**

1/2 (2x+4)(x+3) = 56 x^2+5x-50 = 0 (x+10)(x-5) = 0 ...

**Math**

1.5km/16km = 3/32

**Calculus**

e=2.718 so, the abs error is 2.718-2.68 = 0.038 as a % error, that is .038/e = 1.39%

**Geometry**

If the point directly below the top of the tree is x feet from the base, then we have h/(x+10) = tan61° h/x = tan78° eliminating x, we get the height h/tan61° - 10 = h/tan78° h = 10(cot61°-cot78°)

**Math**

csc60° * cot 30° * tan 60° = 2/√3 * √3 * √3 = 2√3 2sec^2 45° cos30° = 2*2*√3/2 = 2√3

**Geometry**

(25/35)^3 = (5/7)^3

**math**

4D coefficients require a variable. The 6 is just a constant, not a coefficient of x. 7A Total is just the sum: 6t+2 + 9t-6 = (6+9)t+(2-6) = 15t-4 15A (1.8 x 10^1)(7 x 10^5) = (1.8x7)x10^(1+5) = 12.6x10^6 = 1.26x10^7 18D -x(5x-4) = -x*5x -x(-4) = -5x^2 + 4x Look again at your ...

**Algebra**

If x is the smaller voltage, then x+32 is the larger one. x + x+32 = 126 Now find x, and you have the smaller voltage.

**Maths**

since the right side of the intervals are at 9,10,11 just add up (1)* f(9)+f(10)+f(11) Again use the right sides, of width 2/3 each, to get (2/3)*(f(-7/3)+f(-5/3)+f(-1)) Do the left sums similarly, using the appropriate widths.

**Geometry**

9 edges Euler's formula: V-E+F = 2

**math(urgent)**

.75p = 1200, so the original price p=1600 Since the profit was 10% of 1200, the cost was 1080. At 1600, the profit would be 520, or 32.5% of the selling price. I gotta admire you syntax on that (c) part. That simply cannot be how the question was worded . . .

**MATH GEO URGENT**

Since opposite angles are supplementary, we have 2x+4x = 180 x = 30 and the angles are 60,90,120,90

**math 1 question!!!!!!**

so, yes, B is the answer to the question asked. :-)

**Statistics/ is this how I do it.**

add and divide by 5 gives the mean, not the range the range is hi-low = 103-83=20 The mean is 96.4 To find the std, (1) take the difference of each value from the mean (2) square that difference (3) add up all those squares (4) take the square root. That is the std. Better rev...

**Math**

X is 5 by 10 Y:x = 4/3, so Y is 20/3 by 40/3 and its perimeter is thus 40 or X is 5 by 10, so its perimeter is 30 Y:X = 4:3, so its perimeter is 40

**math**

6b/3a + b/a = 6b/3a + 3b/3a = 9b/3a = 3b/a or 6b/3a + b/a = 2b/a + b/a = 3b/a

**math**

well, what's 1000000/600 * 14 ?

**math**

just multiply by the dimensions: 60m * 25m * 7m = 10500 m^3

**math**

Looks like this question has been done several times. Check the Related Questions links below.

**Algebra 1**

Same old parenthesis-free exposition. Surely by now you can factor the expressions and eliminate common factors. Take a look at http://www.wolframalpha.com/input/?i=%28%283h^3+-+6h%29%2F%2810g^2%29%29+*+%28%284g%29%2F%28g^2+-+2g%29+%29 and notice how the parentheses make thing...

**math**

how many from 11:35 to 12:00? how many from 12:00 to 12:50? Now add them up...

**math**

34/d = cos 72° now just solve for d.

**HELP!!!!**

correct

**Math HELP**

Just read the words and write as symbols. The number of apples in an apple tree n after subtracting by 6, n-6 multiplying by 6, (n-6)*6 dividing by 6, (n-6)*6/6 equals 6. (n-6)*6/6 = 6 n-6 = 6 n = 12 books = x a = x/2 + 1 b = (x-a)/2 + 2 c = (x-a-b)/2 + 3 x-a-b-c = 3 make all ...

**MATH**

LCD = (k-3)(k+3) = k^2-9

**math**

well, clearly, a is 11 or 18 b is 5 Now pick the correct answer.

**trig**

you are correct

**Geometry**

well, you know that each sphere holds 3392.92/30 = 113.097 so, now you know that 4/3 pi r^3 = 113.097, so r = 3

**math**

4770(1+r/4)^(4*3) = 8233 (1+r/4)^12 = 1.726 1+r/4 = 1.0465 r/4 = .0465 r = .186 = 18.6%

**Math**

6700(1+.046/2)^(2*15) = 13253.90

**algebra**

Do you mean (x^10 + 5x^9 + 4x^8)/(x+2) ? If so, then you have x^8(x^2+5x+4)/(x+2) x^8(x+1)(x+4)/(x+2) but I don't see what that has to do with the Binomial Theorem.

**Math**

Draw a Venn diagram. Look for the intersections. For this problem, let the two circles represent how many people eat meat an d fish, respectively. In this case, 2 eat both. So, put a 2 in the place where the two circles intersect. Now, since we know that 6 eat meat, and we'...

**Algebra 1--Please, help me!**

#1 I get 2n^2/(n-6) #2 (2x^2 + 8x + 6)/x / (2x^2 + 2x)/(x^3 - x^2) 2(x+1)(x+3)/x / 2x(x+1)/x^2(x-1) (x+3)/(x-1) #3 8b^3c/b^2c / (4b^2 + 4b) 8b / 4b(b+1) 2/(b+1) Next time, show your steps. You are evidently taking some wrong turns.

**Algebra 1--Please, help me!**

Man, you gotta start using parentheses. Can't you see how hard it is to separate the terms and factors? #1 and #2 are ok #3 3h(h^2-2)/10g^2 * 4g/g(g-2) I suspect a couple of typos, so I will say it's (3g^2-6g)/10g^2 * 4g/(g^2-2g) 3g(g-2)/10g^2 * 4g/g(g-2) 3(g-2)/10g * ...

**Trig**

If you measure the temperatures and plot them, the curve is sinusoidal. This is mainly because the earth is a sphere rotating in space, relative to the sun. As the sunlight hits the surface, it causes the temperatures to rise, but then the earth turns away, and they fall again...

**Algebra**

6e^-x = 3 e^-x = 1/2 e^x = 2 x = ln 2 32(1.5)^x = 640 1.5^x = 20 x ln 1.5 = ln 20 x = ln20/ln1.5 and similarly for the others. If you get stuck, come on back and show what steps you took. Just remember that log and exponents are inverse operations. Just as with roots, if you k...

**algebra**

speed = distance/time So, you want 20/1.2 - 20/1.6 = ?

**geometry**

The slope of a line does not change. The length expands by the dilation factor.

**algebra**

so, how many watts per decibel? Divide that into 2.42*10^-5 what's this "cross"? Can't you say "times", or use the multiplication symbol?

**math**

(1) The sides are x and y, so y = 400-x The area is thus a = xy = x(400-x) (2) If the side x is parallel to the water, x+2y = 400, so y = (400-x)/2 and the area is a = xy = x*(400-x)/2 (3) x+y=200, so the area is a = xy = x(200-x) If you need to find the maximum area, just rem...

**algebra**

3 = x-3 6 = x As for the other, I can't quite decode your weird text. I can say that ln e = 1 ln √n = 1/2 ln n ln a - ln b = ln(a/b) If you have ln e = ln √6 - 3ln x 1 = ln√6 - ln x^3 1 = ln √(6/x^6) e = √(6/x^6) 6/x^6 = e^2 x^6 = 6/e^2 x = (6...

**Precalculus**

y=2*pi*x*(25-x)^2

**college algebra**

If the numbers are x-1,x,x+1, then 3x = 651 x = 217 So, the numbers are 216,217,218 Don't know what was all that stuff with factors of 651. Looks like you need to study what "sum" and "consecutive" mean. The two paychecks are p and .75p. So, p + .75p = ...

**Algebra**

Reference angles are always measured from the x-axis. So, since 3pi/4 = pi - pi/4, the reference angle is pi/4. Better go back and review that topic some.

**college algebra**

you are mixing up all kinds of unrelated numbers, and then throwing darts at the calculations. If x is the slower rate, then 3x is the faster rate. So far so good. Now consider that distance = time * speed, and the total distance covered is 64 miles. Since the time for both ri...

**MATH**

a rational number can be written as a fraction. Any terminating or repeating decimal is also rational. √5 is not rational. There is no fraction which is exactly equal to √5. The decimal value goes on forever and never repeats. It is easy to prove that √5 is i...

**Math - incomplete**

don't you see that there's something missing here?

**Algebra 2**

OK. You do understand that if the sides of the rectangle are x and y, then the area is a = xy right? Given the equation of a parabola, can you find the vertex? If y = ax^2+bx+c, then the vertex is at x = -b/2a So, in each case, figure out what x and y are, express the area a a...

**Algebra 2**

(1) The sides are x and y, so y = 400-x The area is thus a = xy = x(400-x) (2) If the side x is parallel to the water, x+2y = 400, so y = (400-x)/2 and the area is a = xy = x*(400-x)/2 (3) x+y=200, so the area is a = xy = x(200-x) If you need to find the maximum area, just rem...

**Geometry**

the car moves as far as 10 times the circumference of the wheel. C = pi*d, so C = 22pi = 69.11 inches so, the car moves 691.1 inches, or 57.6 ft

**Algebra**

correct

**Math**

v = 15000 * .7^t

**Algebra, math**

If the plane's speed is p and the wind's speed is w, then 1200/(p+w) = 3 1200/(p-w) = 4 rearrange to get 3p+3w = 1200 4p-4w = 1200 or, p+w = 400 p-w = 300 Now just solve for p and w.

**How many terms are in the following polynomial?**

the powers don't really matter. The terms are separated by the + and - signs. So, just count them and add 1.

**Math**

You are correct in counting 2 coefficients. But, they are both positive, so (b) is correct.

**College Algebra**

better to use time = distance/speed, since we are adding up times here. d/35 + 15 + d/50 = 41 17/350 d = 26 d = 26 * 350/17 d = 9100/17 = 535.29 check: 535.29/35 = 15.294 535.29/50 = 10.706 total driving time is 26 hours, as expected.

**MATH PLZ HELP**

NO. The answer is 10/14 since there are 10 not-pink erasers out of 14 total.

**MATH PLZ HELP**

how many of the erasers are not pink? How many total erasers are there? P(~pink) = #~pink/#total

**Math**

No reason to try to use decimals. Fractions are exact. Your addition is correct.

**Maths ,science**

12000(1+.065)^5

**Trig**

The angle is θ, where tanθ = (173-5)/50

**statistics**

75 is 5 std from the mean of 60, so 1 std must be 3.

**Test and Measures**

In that case, you need to review what the Z table means. Without that, you have no context. A Z score of zero means that the value is 0 std away from the mean. In this case, it means that the score is the same as the mean, or 65. If such a question is assigned, it can only ind...

**Test and Measures**

what score is 0 std from the mean of 65?

**science**

Each mole of Pb(NO3)2 will make one mole of PbO So, how many moles of Pb(NO3)2 are in 4.0 grams? What is the mass of that many moles of PbO

**Geometry**

you need factors of 39 which differ by 10. I suggest 3 and 13. So, x^2-10x-39 = (x-13)(x+3)

**math**

initial velocity is 800 ft/s upward it does not change the equation. initial position is 0, since it was fired from the ground (height=0) It falls back to the ground when h=0. So, solve for t in 800t-16t^2 = 0 Solve for t in 800-16t^2 = 6400 (why are there two solutions?) Same...

**geometry**

If the length is x, then 20/x = sin 75.5° Now just solve for x.

**math**

1/a + 1/b + 1/c = 2 If we let a <= b <= c, then there's always the easy case where a=1 b=2 c=2 I guess that's the only one, since if any of the three values is 3 or more, then the fractions can't add up to 2.

**Algebra**

x^2+6x+8 = 0 (x+2)(x+4) = 0 Since (x+a)(x+b) = x^2 + (a+b)x + ab you are looking for factors of 8 that add up to 6. 5w^2-3 = 0 5w^2 = 3 w^2 = 3/5 w = ±√(3/5)

**Math**

If she started with x dollars, 4/9 x = 20b x = 45b 10b + 5d = 5/9 x We want the ratio d/b. So, 10b + 5d = 5/9 * 45b 10b + 5d = 25b 5d = 15b d/b = 3

**math**

The cat runs 4/7 as fast as the dog. So, if the dog has to run x meters, the cat will have run 4/7 x during that time. x = 12 + 4/7 x 3/7 x = 12 x = 28 That is, the cat will have run 16 meters while the dog runs 28 meters, having made up the cat's 12-meter head start.

**Math 8th grade**

Take a look at the last terms: x and 3x-2 So, for all the other places where x is given, y = 3x-2 Where y is given, x = (y+2)/3 Now just fill in the blanks.

**Math**

a = -12 d = 3 S = n/2 (-12 + 39) Your mission, should you choose to accept it, is to figure out how many terms there are (n) from -12 to 39

**math**

If there are x ounces of the cheap tea, then the rest (32-x) is expensive. The cost of the mix must be the total of the costs of the components, so 3.99x + 8.99(32-x) = 5.99*32 Now just solve for x.

**algebra**

2x-x^3 >= 0 x(2-x^2) >= 0 This function crosses the x-axis at the roots, which are at x = -√2, 0, √2 Now, you know that y is negative for large negative x, so y < 0 in (-∞,-√2) y >= 0 in [-√2,0] y < 0 in (0,√2) y >= 0 in [&...

**College Algebra**

The common denominator is 2(x-2). If you multiply through by that, you get x - 7*2(x-2) = 1*2 Now just proceed normally: x - 14x + 28 = 2 -13x = -26 x = 2 For the next one, you must be interpreting the equation as 1/(2y) + 4 = 1/(7y) if you multiply by 14y, you get y + 4*14y =...

**College Algebra**

How did it not work out? Show us what you tried and why you think it's wrong...

**College Algebra**

2/9 + -5/6 = -8 - (-3/7 k) 2/9 - 5/6 + 8 = 3/7 k 133/18 = 3/7 k 931/54 = k I suspect a typo. Show your steps, as I see no way to get 82k from that input.

**algebra**

Assuming a typo, and you meant peanuts instead of almonds, we have 2.95p + 7.95(80-p) = 6.50*80 p = 23.2 So, 23.2 lbs of peanuts and 56.8 lbs of cashews or whatever the nuts really are.

**Math**

If the base of the triangle is 2b, then b/h = tanθ, so b = h tanθ The area A = 1/2 (2b)(h) = bh = h^2 tanθ So, θ = arctan(A/h^2)

**geometry**

All I see is a then-clause. No conditions appear to be involved. But, I suppose you could say If: the product of x and y is an odd multiple of 5 AND: x and y are integers Then: x or y is a multiple of 5 AND x and y are odd Without those AND conditions, not much can be said abo...

**algebra**

If you plot both values on the number line, you will see that -2/3 is to the right of -1, so the statement is false.

**Math Algebra**

Assuming you mean 2/(3x) + 4/x = 7/(x+1) then multiply through by (3x)(x+1) and you have (with x≠0 or -1) 2(x+1) + 4*3(x+1) = 7(3x) 2x+2 + 12x+12 = 21x 7x = 14 x = 2

**decimals**

The number is a.bcd the digit in the hundreths place of 4.361 is 6, so, c>6 the digit in the tenths place of 2.85 is 8, so d>8 a.b = 8.6 So, we have 8.6[789]9 where the 3rd digit can be any of those in brackets.

**Math**

1. No - surely you have drawn pgrams which are not squares. 2. No - but 3. Yes 4. Yes 5. No - a rhombus has all sides equal Looks like you need to review your definitions some, and play around drawing some figures, with sides of various lengths and slants.

**Mathamatics**

you don't solve an identity -- you prove it. 1-cos^2θ = sinθ cosθ/cotθ since cotθ = cosθ/sinθ, now we have sin^2θ = sinθ sinθ QED (1-cos^2θ)(1-tan^2θ) = (sin^2θ-2sin^4θ/(1-sin^2θ) sin^2θ(1-tan^...

**Harris**

that would be 2(3x + 5 + x +7) = 8x+24

**Math**

these are all standard angles you should know by heart. It will save you a lot of trouble working them out all the time. -1 - 1 + 1 - 2 + 2 + 1 = 0 It also involves knowing the signs of the trig functions in the various quadrants, and how to figure the reference angle. Also, l...

**Math**

5{3a-2b(3a+6b)+6a} 15a-10b(3a+6b)+30a 15a-30ab-60b^2+30a 45a-30ab-60b^2

**Geometry**

I'm sure the question is correct. You probably want to know whether your answer is correct. I believe you are right in your choice.

**Math**

If you want to use vector notation, then if the vector to A is a, and to B is b, etc. Then AB = b-a BC = c-b CA = a-c AB+BC+CA = b-a+c-b+a-c = 0 AB is b-a because if there is a vector u such that a+u=b, then u=b-a.

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