Q:
Suppose a laboratory has a 57 g sample of polonium-210. The half-life of polonium-210 is about 138 days.
a. How many half-lives of polonium-210 occur in 276 days?
b. How much polonium is in the

sample 276 days later?
A.
2; 14.25 g
B.
2; 28.5 g
C.
3; 7.13 g
D.
2; 3,933 g

A: A. 2; 14.25

Expert answered|rickjames|Points 761|

Expert answered|rickjames|Points 761|

Question

Asked 6/7/2012 11:12:45 AM

Updated 4/26/2014 11:59:22 AM

1 Answer/Comment

Rating

3

(a^-12 b^-8)/(a^-2 b^-11)

= a^-10 b^3

= b^3/a^10

= a^-10 b^3

= b^3/a^10

Added 4/26/2014 11:59:22 AM

This answer has been confirmed as correct and helpful.

Confirmed by jeifunk [4/26/2014 12:05:07 PM]

Find the slope and y-intercept of the line.
18x + 2y = –36 **Weegy:** .Write y =1/4 x + 6 in standard form using integers.
A.4x – y = 24
B.–x + 4y = 24
C.–x – 4y = 24
D.–x + 4y = 6
**User:**
The grocery store sells kumquats for $3.75 a pound and Asian pears for $2.25 a pound. Write an equation in standard form for the weights of kumquats k and Asian pears p that a customer could buy with $22.
A.
3.75p + 2.25k = 22
B.
3.75k + 2.25p = 22
C.
3.75 + 2.25 = k
D.
3.75k = 2.25p + 22 (More)

Question

Expert Answered

Updated 6/26/2014 4:15:28 PM

2 Answers/Comments

18x + 2y = –36 in y = mx + b form is y = -9x - 18, where m stands for slope. Therefore, the slope is -9.

To find the y-intercept, let x = 0.

y = -9x - 18;

y = -9(0) - 18;

y = 0 - 18 = -18

Slope: -9

Y-intercept: -18

To find the y-intercept, let x = 0.

y = -9x - 18;

y = -9(0) - 18;

y = 0 - 18 = -18

Slope: -9

Y-intercept: -18

Added 6/26/2014 4:15:28 PM

This answer has been confirmed as correct and helpful.

Solve the system using elimination.
7x + 5y = 15
–6x – 4y = –14
A.
(–4, 5)
B.
(–6, 7)
C.
(7, –7)
D.
(5, –4)

Question

Not Answered

Updated 11/24/2014 6:35:54 AM

1 Answer/Comment

The solution set for 7x + 5y = 15, –6x – 4y = –14 is (5, –4).

(7x + 5y = 15) * 6;

42x + 30y = 90;

(–6x – 4y = –14) * 7;

-42x - 28y = -98;

(42x + 30y = 90) + (-42x - 28y = -98);

2y = -2; y = -8/2; y = -4;

7x + 5y = 15;

7x + 5(-4) = 15;

7x - 20 = 15;

7x = 15 + 20;

7x = 35;

x = 35/7; x = 5

(7x + 5y = 15) * 6;

42x + 30y = 90;

(–6x – 4y = –14) * 7;

-42x - 28y = -98;

(42x + 30y = 90) + (-42x - 28y = -98);

2y = -2; y = -8/2; y = -4;

7x + 5y = 15;

7x + 5(-4) = 15;

7x - 20 = 15;

7x = 15 + 20;

7x = 35;

x = 35/7; x = 5

Added 11/24/2014 6:35:54 AM

This answer has been confirmed as correct and helpful.

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