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4 years ago

Solve x2 - 8x = 20 by completing the square. Which is the solution set of the equation?

Mathematics

1 answer:

Artyom0805 [142]4 years ago

3 0

Answer:

{-2,10}

Step-by-step explanation:

x^2 - 8x = 20

Take the coefficient of x

-8

Divide by 2

-8/2 =-4

Square it

(-4)^2 =16

Add this to each side

x^2 - 8x+16 = 20+16

x^2 - 8x+16 = 36

The left hand side becomes( x + (-8/2) )^2

(x - 4)^2 = 36

Take the square root of each side

sqrt((x - 4)^2) =±sqrt( 36)

x-4 = ±6

Add 4 to each side

x-4+4 = 4±6

x = 4±6

x = 4+6 x = 4-6

x = 10 x = -2

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Answer and Step-by-step explanation:

The computation is shown below:

Let us assume that

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Given that

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3 years ago

A boy has only dimes and quarters in his piggy bank. if he has 70 coins worth 12 dollars and 40 cents altogether, how many quart

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Let us bear in mind the equivalent value of these coins:

One dime = $0.10

One quarter = $0.25

Let x = number of dimes

y = number of quarters

Since the boy has 70 coins in total, we can say that:

x + y = 70 (can be written as x = 70 – y)

Since the boy has a total of $12.40, we can say that:

0.10x + 0.25y = 12.40

To solve this problem, we need to solve this system of equation. We have to substitute the value of x as written in the first equation (x = 70 –y)

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