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3 years ago

15

The ten digit number of a two-digit is twice the units digit . If the digit are reversed the new number is 18 less than the orig

inal number . Find the number.

1 answer:

STALIN [3.7K]3 years ago

8 0

The two digit number can be:

21, 42, 63, 84

Now reverse those numbers and subtract to find one with a difference of 18:

21 - 12 = 9

42 - 24 = 18

The number would be 42.

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A certain college graduate borrows 7864 dollars to buy a car. The lender charges interest at an annual rate of 13%. Assuming tha

White raven [17]

Answer:

Therefore rate of payment = $ 3145.72

Therefore the rate of interest = =$1573.17

Step-by-step explanation:

Consider A represent the balance at time t.

A(0)=$ 7864.

r=13 % =0.13

Rate payment = $k

The balance rate increases by interest (product of interest rate and current balance) and payment rate.

$\frac{dB}{dt} = rB-k$

$\Rightarrow \frac{dB}{dt} - rB=-k$ .......(1)

To solve the equation ,we have to find out the integrating factor.

Here p(t)= the coefficient of B =-r

The integrating factor $=e^{\int p(t) dt$

$=e^{\int (-r)dt$

$=e^{-rt}$

Multiplying the integrating factor the both sides of equation (1)

$e^{-rt}\frac{dB}{dt} -e^{-rt}rB=-ke^{-rt}$

$\Rightarrow e^{-rt}dB - e^{-rt}rBdt=-ke^{-rt}dt$

Integrating both sides

$\Rightarrow \int e^{-rt}dB -\int e^{-rt}rBdt=\int-ke^{-rt}dt$

$\Rightarrow e^{-rt}B=\frac{-ke^{-rt}}{-r} +C$ [ where C arbitrary constant]

$\Rightarrow B(t)=\frac{k}{r} +Ce^{rt}$

Initial condition B=7864 when t =0

$\therefore 7864= \frac{k}{r} - Ce^0$

$\Rightarrow C= \frac{k}{r} -7864$

Then the general solution is

$B(t)=\frac{k}{r}-( \frac{k}{r}-7864)e^{rt}$

To determine the payment rate, we have to put the value of B(3), r and t in the general solution.

Here B(3)=0, r=0.13 and t=3

$B(3)=0=\frac{k}{0.13}-( \frac{k}{0.13}-7864)e^{0.13\times 3}$

$\Rightarrow- 0.48\frac{k}{0.13} +11614.98=0$

⇒k≈3145.72

Therefore rate of payment = $ 3145.72

Therefore the rate of interest = ${(3145.72×3)-7864}

=$1573.17

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What is the volume of the triangular prism below?

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B is the correct answer

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2 years ago

Pineapples cost $2.50 each and mangos cost $1.50 each. Tim purchased 15 pieces of fruit for $29.50. How many pineapples and how

kotykmax [81]

We can create equations to solve this.

2.50p + 1.50m = 29.50
p + m = 15

Solve for a variable in the 2nd equation and use the substitution method to solve.

p + m = 15

Subtract p to both sides:

m = -p + 15

Plug in -p + 15 for m in the first equation.

2.50p + 1.50(-p + 15) = 29.50

Distribute:

2.50p - 1.50p + 22.50 = 29.50

Combine like terms:

p + 22.50 = 29.50

Subtract 22.50 to both sides:

p = 7

Now plug this into any of the two equations and solve for the other variable.

p + m = 15

7 + m = 15

Subtract 7 to both sides:

m = 8

So he purchased 7 pineapples and 8 mangos.

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Step-by-step explanation:

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