Pei-Hsin Lin 林培心 🌸

1. Communauté
2. Study Group
3. Inverse Fucntions

STEP 1 For a given f(x), set f(x) = y. STEP 2 Isolate x in terms of y. STEP 3 Set x = f⁻¹(y). Note that this process does not always yield a function. Many rational functions are not invertible. If...

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2. Study Group
3. Quadratics (again; please help!)

Hi Bailey, Use the distributive property in reverse here. Factor out the 3 in both terms of the numerator. 3 ÷ 3 = 1. Any number divided by itself equals 1. The simplified result is just all that's...

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2. Study Group
3. Need explanation for a math question

If you think about it in terms of money, two debts put together make an even bigger debt. (-3)³ - 4² =-27 - 16 =-27 + (-16) = -43 The answer would be 11 if the problem were slightly different. (3)³...

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2. Study Group
3. Arithmetic Sequence

The explicit formula for arithmetic sequences always follows a specific format. The xth term aᵪ is always equal to the first term a₁ plus the common difference d (x - 1) times: aᵪ = a₁ + d(x - 1) I...

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3. decimals to fractions lowest terms.

METHOD 1:  Do the calculation with decimals. Then convert the answer into a fraction. 0.31 - ¼ = 0.31 - 0.25 = 0.06 = 6/100 = 3/50   METHOD 2: Do the calculation with fractions. 0.31 - ¼ =  31/100 ...

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3. imaginary number division

You actually need to multiply by the conjugate on top and bottom; in other words, multiply by (1 - 4i)/(1 - 4i). This is a fancy way to multiply by 1, since any quantity divided by itself = 1. This...

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2. Study Group
3. Absolute value equation graphs

In order to graph h(x) = |2x - 3| - |x + 1| first consider the graphs of  f(x) = |2x - 3|, a v-shaped graph with vertex (³/₂,0) f(x) = -2x + 3 for x ≤ ³/₂ and f(x) = 2x - 3 for x ≥ ³/₂ g(x) = |x + ...

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2. Content Requests and Feedback
3. Informal request

Learning with Khan Academy is a self-investment. Think about it. Are you worth it? (Yes.) You can stay on target by making and meeting shorter-term goals. Try to increase your Mission Progress by 7...

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2. Study Group
3. Inverse Fucntions

Ah, now we're delving into calculus. If f(x) is restricted to the domain (-1,1) and the range (-∞,∞), then f⁻¹(x) is restricted to the domain (-∞,∞) and the range (-1,1). Restriction to the range (...

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2. SAT Questions and Feedback
3. Amazing SAT Practice but not enough Question-Specific Material

Hi Matthew, For help with specific problems, just post your question and the Khan Academy community will try to help you. As for the question you have mentioned: Medicine (M) in milligrams is given...