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dlinn [17]
3 years ago
8

PLEASE HELP!!This is joshs solution for the equation x^2-6x-7=0: x^2-6x-7=0

Mathematics
1 answer:
iren [92.7K]3 years ago
4 0

Answer:

  no. see below

Step-by-step explanation:

This much of Josh's working is correct:

  x^2-6x=7

  x^2-6x+9=7+9

  (x-3)^2=16

At this point Josh apparently overlooked the fact that he needed to take the square root of both sides of the equation. Had he done that, he would have ...

  x -3 = ±4

  x = 3+4 . . . or . . . 3 -4

  x = 7 or -1

_____

Josh reported values of x that would match ...

  x -3 = ±16

He <em>violated the equal sign</em> by taking the square root on the left, and multiplying by ±1 on the right. Doing different operations on the two sides of the equation will mean the value of x is changed to something other than what you're looking for.

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gladu [14]

The value of √(7 * 23 - 1)/8 is 4.47, the values of a, b and c are -14/11, -10/11 and 3, respectively and the area of the shape is 5√5 + 5 square meters

<h3>How to evaluate the radical expression?</h3>

The question goes thus:

If √5 = 2.236, evaluate √(7 * 23 - 1)/8

We have:

√(7 * 23 - 1)/8

Evaluate the product of 7 and 23

√(7 * 23 - 1)/8 = √(161 - 1)/8

Evaluate the difference of 161 and 1

√(7 * 23 - 1)/8 = √160/8

Evaluate the quotient of 160 and 8

√(7 * 23 - 1)/8 = √20

Express 20 as the product 4 and 5

√(7 * 23 - 1)/8 = √(4 * 5)

Expand the product

√(7 * 23 - 1)/8 = √4 * √5

Express √4 as 2

√(7 * 23 - 1)/8 = 2 * √5

Substitute √5 = 2.236

√(7 * 23 - 1)/8 = 2 * 2.236

Evaluate the product

√(7 * 23 - 1)/8 = 4.472

Approximate

√(7 * 23 - 1)/8 = 4.47

Hence, the value of √(7 * 23 - 1)/8 is 4.47

<h3>How to simplify the radical expression?</h3>

The expression is given as:

(3√2 + 5√6)/(3√2 - 5√6)

Rationalize the above expression

(3√2 + 5√6)/(3√2 - 5√6) * (3√2 + 5√6)/(3√2 + 5√6)

Evaluate the product

(3√2 + 5√6)²/((3√2)² - (5√6)²)

Simplify the denominator

(3√2 + 5√6)²/(18 - 150)

This gives

[(3√2)² + (5√6)² + 2 *(3√2) * (5√6)]/(-132)

Simplify the numerator

[168 + 120√3]/(-132)

Simplify the fraction

-14/11 - 10√3/11

Hence, the values of a, b and c are -14/11, -10/11 and 3, respectively

<h3>How to determine the area?</h3>

The area is calculated as:

A = 1/2 * (Sum of parallel bases) * Height

So, we have:

A = 1/2 * (4 + 3√5 + 6 - √5) * √5

Evaluate the like terms

A = 1/2 * (10 + 2√5) * √5

Evaluate the product

A = (5 + √5) * √5

Evaluate the product

A = 5√5 + 5

Hence, the area of the shape is 5√5 + 5 square meters

Read more about rational expressions at:

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You are working for a company that creates tubes that measure 10 cm long and have a diameter of 6 cm. The tubes need to be cut j
Nataly_w [17]

Answer:

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And replacing the value of \pi =3.14 we got:

A = 78*3.14 cm^2= 244.92 cm^2

Step-by-step explanation:

For this case we have the long who represent the height 10 cm and the diameter is 6cm. So then the radius is given by:

r = \frac{D}{2}= \frac{6cm}{2}= 3cm

And the surface area for a cylinder is given by this formula:

A= 2\pi r^2 +2 \pi rh

And replacing the info given we got:

A= 2\pi (3cm)^2 +1 2\pi (3cm)(10 cm)= 18 \pi + 60\pi = 78 \pi cm^2

And replacing the value of \pi =3.14 we got:

A = 78*3.14 cm^2= 244.92 cm^2

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Which is greater, 0.575 or 0.581?
loris [4]

\huge\text{Hey there!}

\large\text{Fun fact: DECIMALS are BELOW ZERO and NON-DECIMALS are ABOVE}\\\large\text{ZERO}

\large\text{\bf{0.581}}\large\text{ is MORE THAN 0.575}\huge\checkmark  

\large\textsf{Good luck on your assignment and enjoy your day!}

~\frak{Amphitrite1040:)}

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3 years ago
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