Mathematics, 26.08.2020 18:01 josiesolomonn1605

Simplify 4\2-root 2 + 5 \root 2-1

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Answer from: mzynique2000

Step-by-step explanation:

Use FOIL method

$(\sqrt{2} -1)(2-\sqrt{2})= \sqrt{2}*2 -\sqrt{2}*\sqrt{2} -1*2-1*(-\sqrt{2})\\\\\\=2\sqrt{2} - 2 -2 +\sqrt{2}$

Combine like terms

$=2\sqrt{2} +\sqrt{2} - 2 -2\\\\\\=(2+1)\sqrt{2} - 4\\\\\\=3\sqrt{2}-4$

$\frac{4}{2-\sqrt{2}}+\frac{5}{\sqrt{2} -1}=\frac{4*(\sqrt{2} -1)}{(2-\sqrt{2})*(\sqrt{2} -1)}+\frac{5*(2-\sqrt{2})}{(\sqrt{2} -1)(2-\sqrt{2})}\\\\\\=\frac{4\sqrt{2}-4+10-5\sqrt{2}}{(\sqrt{2} -1)(2-\sqrt{2})}$

$=\frac{4\sqrt{2}-5\sqrt{2}-4+10}{3\sqrt{2}-4}\\\\\\=\frac{(4-5)\sqrt{2}+6}{3\sqrt{2}-4}\\\\\\=\frac{-1\sqrt{2}+6}{3\sqrt{2}-4}$

Answer from: Quest

step-by-step explanation:

30% of $420 is 0.30($420) = $126 and $420 + $126 = $546.

or, 130% of $420 is 1.3($420) = $546.

notice that this is not the $600 original list price with which we started.

why doesn't this work?

the method does not work because 30% of $420 is not the same amount as the 30% of $600. it may seem obvious when stated this way, but it is a very common error made on problems of this type. we cannot just use the same percent and get back to the original amount because we are taking that percent of a different value.

to work problems of this type correctly, it is generally best to write an equation for the situation and then solve.

example: since (100% – 30%)(original price) = (sale price)

70% of the (original price) is $420.

0.7x = 420

equation image indicator

x = 600

the original cost was $600.

we may also solve this problem using the two-step method. working the problem in two steps requires us to use more algebra skills. we have to know that x = 1x (identity property of multiplicationtext annotation indicator) and that 1x – 0.3x = 0.7x (subtracting like terms). then we solve the problem as follows:

(original price) – 30%(original price) = sale price

x – 0.3x = 420

0.7x = $420

equation image indicator

x = 600

the original cost was $600.

note that with both of the above methods we do obtain the correct original amount.

example: after a 5% pay raise, hermione is earning $22,680 per year. what was she earning before the pay raise?

105% of (original salary) = current salary

1.05x = 22,680

equation image indicator

x = 21,600

hermione earned $21,600 per year before the pay raise.

this is an example so maybe you will get how to at least do it!

Answer from: Quest

c is the correct answer

step-by-step explanation:

9. find the determinant of k. a. 671 b. 913 c. 1 d. 597

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