# Posts by STEVE

Total # Posts: 49,574

**Math**

well 2×15×2 = 60

*February 16, 2017*

**Algebra 1**

Looks like you're a bit off. See http://www.wolframalpha.com/input/?i=solve+y%3D0.081+*+x+%2B+215.378,+y%3D0.222+*+x+-+43.829 Doing the substitution, I get y=0.081 * x + 215.378 so, 0.081x + 215.378 = 0.222x - 43.829 0.141x = 259.207 x = 1838.3475 y = 364.2841 Not sure how...

*February 16, 2017*

**Chem**

N comprises 251/(322+146+251) = 34.9% of the mixture, so ... PV=kT so use that to get V.

*February 16, 2017*

**Math**

well, each side is 17/?2

*February 16, 2017*

**math**

disregarding the units, 2 pi r = 200 pi r = 100

*February 16, 2017*

**Chem**

well, what is the molar mass of NaHCO3?

*February 16, 2017*

**Calculus**

The area is an 8x4 rectangle and a 4x4 square, = 48 Divide that by the interval width and you get 6.

*February 16, 2017*

**physics**

F=ma, so a = 15/4 m/s^2 v=at, so v increases by 4 * 15/4 = 15 m/s p=mv, so p changes by 4*15 = 60 kg-m/s

*February 16, 2017*

**math**

(-6*4x^2*y^3/27xy^4)^1/3 = ((-6/27) x/y)^1/3 = -1/3 ?(6x/y)

*February 16, 2017*

**Math**

no idea on 1 & 3. Picture needed. The others are correct. On #6, it could be any of A,B,C depending on the figure. A is the most general.

*February 16, 2017*

**math**

5+3.25x = 18

*February 16, 2017*

**Math - Sequences**

well, what is 15+1.5? That's the 2nd term, clearly.

*February 16, 2017*

**math**

bh/2 = 110 10h/2 = 110 ...

*February 16, 2017*

**Math (Algebra 2)**

so, why not show your work? P(1+.0939)^10 = 20000 Now just solve for P.

*February 16, 2017*

**math**

x = 3(x+3)-3(x-3) x=18

*February 16, 2017*

**math**

the triangle is half the area of the trapezoid.

*February 16, 2017*

**Math**

ever hear of < and <= and > and >= ? Other than that your answers are ok, assuming the 60 in #2 is a typo.

*February 16, 2017*

**math**

(x,y) is symmetric with (-x,-y) so, what do you think?

*February 16, 2017*

**math**

for any interest rate r compounded n times per year, and time t years, A = P(1 + r/n)^(nt) so, plug in your numbers.

*February 16, 2017*

**urgent math help plz !!**

Assuming you meant sin?=3/4 The hypotenuse is 4, so the other leg is ?(16-9) = ?7 In QII, x<0. Since cos? = x/r cos? = -?7/4 You should immediately have known your answer was wrong, because sin^2? + cos^2? = 1

*February 16, 2017*

**maths**

Draw a circle with bc as diameter. Chords ac and db are the same length, so the subtend the same central angle. So, ac is parallel to bd, and abcd is a rectangle. So you have SAS and congruent triangles.

*February 16, 2017*

**P4 maths**

3x = x/2 + 10 x = 4

*February 16, 2017*

**Math**

(x-1)/2+(x-2)/2+(x-3)/2+...(x-100)/2 1/2 (x-1 + x-2 + x-3 + ... + x-100) = 1/2 (x+x+x... - (1+2+3..+100)) = 1/2 (100x - 100*101/2) = 50x - 2525

*February 16, 2017*

**Math - Calculus**

since |sinx| <= 1, x^2 sin(1/x) < x^2. So, since x^2 -> 0, so does x^2 sin(1/x) x^2 sin(1/x) does not exist when x=0, but since f(0)=0, f is continuous. [(0+h)^2 sin(1/(0+h)) - 0^2*sin(1/0)]/h = [h^2 sin(1/h) - 0]/h = h^2 ((1/h) - 1/3! (1/h^3) + ...)/h = (h - h/3...

*February 16, 2017*

**pre algebra**

note that as x changes by 1, y changes by 3 So, start with y=3x But, y(0) = 8, so use y=3x+8 check to be sure it fits all the pairs. It does.

*February 16, 2017*

**Math**

correct.

*February 16, 2017*

**Maths**

value is .85 * .88 * .88 = 0.6582 so, it has lost 34.18% Looks like you'd better show your work, huh?

*February 15, 2017*

**Calculus**

correct

*February 15, 2017*

**precalculus**

GCD(42,70) = 14, so ...

*February 15, 2017*

**math**

If you can construct a 60°, bisect it and you have your 30° angle. Build from that.

*February 15, 2017*

**Calculus Question! ASAP!**

you can do the trig stuff, but why bother? let u = 9-x^2 du = -2x dx and the integrand becomes -1/2 u^(-1/2) du and integrates to - u^(1/2) = -?(9-x^2) As for the trig, you cannot take ?(1-sec^2) since sec^2 is always greater than 1, and you don't have a real value. I'...

*February 15, 2017*

**Math**

I'd suggest 4, since it is the greatest common factor of 20,32,64

*February 15, 2017*

**Math**

just multiply 4x5 by 1/2 and 5/4: 2x2.5 and 5x6.25

*February 15, 2017*

**Calc**

f(x) = ?[x,x^8] ln(t) dt The 2nd fundamental theorem is really just the chain rule. f'(x) = ln(x^8)*8x^7 - ln(x)*1/x = 8lnx*8x^7 - ln * 1/x = lnx (84x^7 - 1/x) This works because if g(t) = ?lnt dt g'(t) = ln(t) So, f(x) = g(x^8) - g(x) so, f'(x) = g'(x^8)*8x^7...

*February 15, 2017*

**Math**

yes.

*February 15, 2017*

**too-hard probability sir damon/reiny/steve help**

I get 5/14 = 0.3571 Damon's answer above is P(b=2)/P(w?0) = 0.3546 Seems they ought to be the same ...

*February 15, 2017*

**Math**

1. use the Angle Bisector Theorem. 2. The volume of oil is the area of a circular cap times the length. So, the the formula for the area of a circular cap. Then if the oil volume is v, the depth would have been (v/60?)*15 3. Consider the problem in 2D, and draw a rectangle. If...

*February 15, 2017*

**Math**

m(PQS) + x = 180

*February 15, 2017*

**maths**

a(r^4-1)/(r-1) = 30 a + ar^3 = 18 (r^4-1)/((r-1)(1+r^3)) = 5/3 3r^4-3 = 5r^4-5r^3+5r-5 2r^4-5r^3+5r-2 = 0 (r-1)(r-2)(r+1)(2r-1) = 0 r = 1/2, 1, 2, -1 r=1,-1: extraneous solutions r=2: 2,4,8,16,... r=1/2: 16,8,4,2,...

*February 15, 2017*

**math**

ever think of using math notation instead of words? f(x) = 4x for x <= 3 7-x for x > 3 ?[1,7] f(x) dx = ?[1,3] 4x dx + ?[3,7] 7-x dx = 2x^2[1,3] + 7x - x^2/2 [3,7] = [(2*3^2)-(2*1^2)]+[(7*7-7^2/2)-(7*3-3^2/2)] = 16+8 = 24

*February 15, 2017*

**math**

3 log(u^2/v) 3(2logu - logv)

*February 15, 2017*

**math 103**

the lines intersect at (15,20) The new line has slope -3/5, so it is y-20 = -3/5 (x-15) now massage that into the form you want.

*February 15, 2017*

**Math**

not 810, but vh=810*cos42 Read the information that was given to you.

*February 14, 2017*

**math**

With 90 cattle, he has 9/4 as many mouths, so 4/9 as long to eat: about 16 days

*February 14, 2017*

**Pre calculus**

I cannot find a function of the form 80 + a*e^(-kx) which fits more than two of the points, since when x=0, you have 80+a=176, so a=96 and when x=1 you have 80+96e^-k = 169 e^-k = 89/96 k = ln(96/89) = 0.07571 80+96e^(-0.0757x) does not fit any of the other points.

*February 14, 2017*

**Math**

Each inch has 8 1/8-inch parts. So, 3 1/2 inches is 28 times as long. so, ... or, each inch represents 8 feet. so, 3.5 inches is ? feet

*February 14, 2017*

**Math**

terms are separated by + and - signs.

*February 14, 2017*

**math**

If you plug in your numbers here http://davidmlane.com/hyperstat/z_table.html You will see that it is the 87th %ile.

*February 14, 2017*

**Maths**

p+q = 150 3/4 p = 2/5 q I suspect a typo, as the solution is not an integer.

*February 14, 2017*

**Physical Science**

thank you

*February 14, 2017*

**Physical Science**

A delivery man pushes the button to ring the doorbell. Which of the following forms of energy is not involved in this process? electrical sound mechanical gravitational my answer is gravitational

*February 14, 2017*

**Geometry**

You have 4 sides. Add 'em up and subtract from 30 to get the 5th side. Now, how many are equal?

*February 14, 2017*

**Algebra**

a) which two factors of 6 add to 5? b) which two factors of 6 differ by 1? c) which two factors of 6 add to 1?

*February 14, 2017*

**Algebra**

even integers differ by 2, so the three numbers are x, x+2 and x+4. Now you are told that x(x+2) = 11(x+4)-8 Now solve for x.

*February 14, 2017*

**Math Calc**

the range for an angled shot is R = v^2/g sin2? so, plug in your numbers. Remember to convert ft/s to mi/hr.

*February 14, 2017*

**Math - Calculus**

Recall that the vertical height h is h(t) = 6 + (810 sin42)t - 16t^2 so, just solve for t when h=0.

*February 14, 2017*

**Algebra**

C = P if 0 < P <= 100 Now you can do the part where P > 100, right?

*February 14, 2017*

**Math**

No. That is only the numbers between 0 and 15. You are not restricted to positive values.

*February 14, 2017*

**Math**

real numbers that are less than 15 means s<15

*February 14, 2017*

**College Algebra**

see related questions below...

*February 14, 2017*

**Math 115**

In the first 30 minutes you have walked 3 miles. Then, after a total of 40 minutes, you start walking again. So, D(t) = 3 + 1/60 (t-40) if 40 < t <= 65

*February 14, 2017*

**Calculus**

Since the fraction is pointless as written, I assume you meant M = (log(E)-11.4)/1.5 1.5M = log(E)-11.4 log(E) = 1.5M+11.4 E = 10^(1.5M+11.4)

*February 14, 2017*

**Exponential Equation**

the ^ is used for exponents. I think he means 2e^x^2 + e^x = 4 sometimes they use ^x for ?x In either case, the equation seems unlikely. What do you say, Jason?

*February 14, 2017*

**Exponential**

Just use the usual growth formula. It took 388 years, so 24e^(388r) = 4*10^12

*February 14, 2017*

**algebra**

correct. It can't get from -2 to 6 without going through 0 somewhere in between. You also need to mention that f(x) is continuous. That is necessary.

*February 14, 2017*

**Alebra 2**

recall that x = r cos? y = r sin? now just plug in your numbers.

*February 14, 2017*

**Algebra**

?((-12+2)^2+(-19+3)^2)

*February 14, 2017*

**Mathematics**

No way. I don't think you mean "permuted." Maybe a bit more explanation of the problem would make it clearer just what you have in mind.

*February 14, 2017*

**maths**

7/12 as many stories -- 7/12 as long to type them.

*February 14, 2017*

**Math**

You are correct

*February 14, 2017*

**Data**

Number the pairs 11 22 33 44 55 66 Now, the left shoes can be arranged in 6! ways. For each of those ways, there are 6! ways to arrange the right shoes. Of those, there are 5! arrangements with one matching pair 4! with two matches, ... 1! with 6 matches. So, it seems to me ...

*February 14, 2017*

**Grade 6: money and measures**

1.50n + 10.00*floor(n/30) = 450 n = 246.7 Check: 246 games: 246*1.50 + 10*8 = 449.00 Add $1.50 for the 247th game, and that puts him over the top.

*February 14, 2017*

**algebra**

x/15 = cos75

*February 14, 2017*

**math**

(1 1/4)^2 = (5/4)^2 = 25/16 ft^2

*February 14, 2017*

**Vectors Q#2**

Try reading this discussion. It is the same problem, different points. http://math.stackexchange.com/questions/1300484/distance-between-line-and-a-point

*February 14, 2017*

**Math**

13^2

*February 14, 2017*

**Vectors - Maths**

since CD = CB, vector CD = v If we let AD be vector z, then u.z = (x-v).(x+v) = x.x-v.v Since |x| = |v|, that is zero. So, u and z are perpendicular.

*February 14, 2017*

**Dependent and Independent variables**

a. pick some values for x, and then calculate y. b. pick two of the (x,y) pairs and plot them on graph paper. Draw a line through the two points. All of the other points in your table will also lie on this line. If they do not, you have made a mistake. c. x is independent. You...

*February 13, 2017*

**algebra**

w(2w+4) = 48 w(w+2) = 24 4*6 = 24 4*12 = 48 or, you can solve the quadratic.

*February 13, 2017*

**Precalculus**

one way: determine where a perpendicular line intersects each, and find the distance between the two points of intersection. another way: determine the equation of one of the lines, then find the distance to it from a point on the other line, suing the formula d = |Ax+By+C|/?(...

*February 13, 2017*

**math**

c = 5.00 + 1.50t

*February 13, 2017*

**Algebra**

distributive better go back and read up on both topics

*February 13, 2017*

**Geomety**

well, 2?r^2+2?rh = 500 2?rh = 320 So, 2?r^2 = 180 ?r^2 = 90

*February 13, 2017*

**Calculus**

You need to know the slope of the glider's descent. If he drops straight down, there is no triangle. That is, you need to know his horizontal speed. The vertical drop of 50 ft/s is no good by itself.

*February 13, 2017*

**Math**

If the string covers the entire surface area, consider it a bunch of 3-inch circles. Now, you have to know the diameter of the string. If it is 1/20 inch, then there will be 16*20 = 320 loops. So, nail that down, and you can answer the question.

*February 13, 2017*

**calculus**

actually, the above solution applies if y is the position function. Since it is itself a rate, you need the average value of the function. That is ?[7,10] x^3+2x^2+3 dx ----------------------------- = 782.25 10-7

*February 13, 2017*

**Math**

220+45h Note that when h=0, there is just the flat fee. Then add 45 each time h increases by 1.

*February 13, 2017*

**into to algebra**

add up the amount of alcohol in each part. It must equal the alcohol in the final mixture: .15*150 + .70x = .45(150+x)

*February 13, 2017*

**Introduction to negative linear relationships**

d = m Maybe you need to specify a bit more.

*February 13, 2017*

**physics**

general equation x = a sin(b(t-c))+d Since equilibrium is x=0, d=0 x = a sin(b(t-c)) the period is 9, so b = 2?/9 x = a sin(2?/9 (t-c)) If it travels .4 m in a cycle, the amplitude is 0.1, so x = 0.1 sin(2?/9 (t-c)) Now we have a problem. If x(0) = -0.1, that is its minimum ...

*February 13, 2017*

**Algebra**

.20x = 1

*February 13, 2017*

**math**

42 lbs

*February 13, 2017*

**099**

4x - 30 = -3x - 32 add 3x to both sides 7x - 30 = -32 add 30 to both sides 7x = -2 divide by 7 x = -2/7

*February 13, 2017*

**099 math**

1st step: lose the parentheses: 2(2x-7)-16=3(-x-7)-11 4x-14-16 = -3x-21-11 . . .

*February 13, 2017*

**Math**

angle C = 85° (180-52-43) Labeling the sides a,b,c opposite angles A,B,C, you want side b, since angle B is the smallest angle. b/sinB = c/sinC b/sin43° = 50/sin85° Now just solve for b

*February 13, 2017*

**science**

it takes (50-30)/10 = 2 seconds to reach the final velocity. s = 30t + 1/2 t^2 Now just plug in t=2.

*February 13, 2017*

**Calculus**

1. Just use the power rule recall that 1/x^2 = x^-2 2. product and chain rule: y = x^5 (1+x)^5 y' = 5x^4 (1+x)^5 + x^5 * 5(1+x)^4 = 5x^4(1+x)^4 (1+2x) 3. quotient rule. Assuming the usual carelessness with parentheses, y = (4-x^2)/(2x+3) y' = [(-2x)(2x+3) - (4-x^2)(2...

*February 13, 2017*

**Algebra**

the slope-intercept rule is called that for a reason... Q2. y=kx, so y/x=k, a constant. You want y such that y/10 = 24/8

*February 13, 2017*