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3 years ago

Solve the system of equations. 8x – 3y = 1 –2x + 3y = 11 A. (–1, –3) B. (–1, 3) C. (2, 5) D. (5, 2)

Mathematics

1 answer:

Makovka662 [10]3 years ago

4 0

Answer:

C. (2, 5)

Step-by-step explanation:

Looking at the answer choices, you can see that solving for y will tell you which choice is correct. We can eliminate x from the equations by adding 4 times the second equation to the first:

(8x -3y) +4(-2x +3y) = (1) +4(11) . . . . . adding the equations to eliminate x

9y = 45 . . . simplified; next we divide by 9

y = 5 . . . . . matches choice C

_____

Check

8(2) -3(5) = 16 -15 = 1

-2(2) +3(5) = -4 +15 = 11 . . . . the answer checks OK in both equations

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Please help with 11c!?

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Answer:

"To the nearest year, it would be about 9 years"

Step-by-step explanation:

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This is compound growth problem. It goes by the formula:

$F=P(1+r)^t$

Where

F is the future amount

P is the present (initial) amount

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Given,

P = 20,000

r = 8% = 8/100 = 0.08

F = double of initial amount = 2 * 20,000 = 40,000

We need to find t:

$F=P(1+r)^t\\40,000=20,000(1+0.08)^t\\2=(1.08)^t$

To solve exponentials, we can take Natural Log (Ln) of both sides:

$2=(1.08)^t\\Ln(2)=Ln((1.08)^t)$

Using the rule shown below we can simplify and solve:

$Ln(a^b)=bLn(a)$

We can write:

$Ln(2)=Ln((1.08)^t)\\Ln(2)=tLn(1.08)\\t=\frac{Ln(2)}{Ln(1.08)}\\t=9.0064$

To the nearest year, that would be about 9 years

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Step-by-step explanation:

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Answer:

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