What is the value of x when f (x) = 4? A. - 2 B. 0 C. 12 D. 20

mars1129 [50]

Answer:

Step-by-step explanation:

This one is simple substitution... at least, substitution is the easiest method. The first equation is 3x – 30 = y and the second is 7y – 6 = 3x

As I look, I see 3 ways to use substitution to solve this:

substitute 7y – 6 for 3x
substitute 3x – 30 for y
solve 3x – 30 = y for 3x and make it equal to 7y – 6

We're going to only use 1 method for the sake of time. Try the other two on your own. Assuming you don't make any mistakes, they will work.

Method 1:

3x – 30 = y

7y – 6 = 3x — initial system of equations

7y – 6 – 30 = y — substitute 7y – 6 for 3x

7y – 6 – 30 = y — marking like terms, bold for constants, underlined for variables

7y – 36 = y — combining the constants and simplifying

Here, you could diverge into multiple paths: add 36 to both sides, subtract y from both sides, divide by 6 OR subtract 7y from both sides and divide by –6 . For the sake of time, I'm subtracting 7y, though I don't like dealing with negatives.

7y – 7y – 36 = y – 7y — subtract 7y from both sides

–36 = –6y — simplify

–36 ÷ –6 = –6y ÷ –6 — divide by –6 on both sides

y = 6 — simplify

Again, we can diverge here: substitute y into 3x – 30 = y or substitute y into 7y – 6 = 3x

I'm going to choose 3x – 30 = y but it will work either way, should you take the time (if you have it) to chase down every path this problem can take.

3x – 30 = y — initial equation

3x – 30 = 6 — substitute 6 for y

3x – 30 + 30 = 6 + 30 — add 30 to both sides to isolate 3x

3x = 36 — simplify the expression

3x ÷ 3 = 36 ÷ 3 — divide both sides by 3 to isolate x

x = 12 — simplify

So, we have x = 12 and y = 6 . We know they work for 3x – 30 = y but not if they work for 7y – 6 = 3x . Let's substitute those in to see if (12, 6) really is the solution point.

7y – 6 = 3x — original equation

7(6) – 6 ≟ 3(12) — substitute 6 for y and 12 for x

42 – 6 ≟ 36 — simplify by multiplying

36 = 36 ✔ — simplify by combining like terms on left side

Success! It works! We have found our solution!

I hope this helps increase your understanding of the concept. Have a great day!

8 0

3 years ago

Please help ASAP I will mark brainlest

morpeh [17]

Answer:

Answer C is the only one in function notation.

Step-by-step explanation:

To find something in function notation, we look for 2 different criteria.

On the left side, it must say f( ), with a variable in the parenthesis.
On the right side, the variable being used must match that from the left side.

Since C is the only one that satisfies both of those needs, we know it is the answer.

3 0

3 years ago

2(c-2) pleaseeee help

Ksenya-84 [330]

Answer

2c-4

step by step explanation

2×(c-2)

2×c=2c

2×2=4

so

2c-4

7 0

3 years ago

Explain Steps. Do not answer. #10 and 11 Questions are in the Picture

svet-max [94.6K]

Answer:

Step-by-step explanation:

For problem 10:

1. AE/ED=AC/CB (Since triangle ABC is similar to triangle ADE, we can determine that the ratio of AE to ED is equal to the ratio of AC to CB)

2. AE/ED=(AE+EC)/CB (Rewrite AC as the sum of the lengths forming it; This is sometimes referred to as the Partition Postulate)

3. 9/x=(9+6)/10 (Substitute the given values into this equation)

4. x=6 (Use algebra to solve for x)

For problem 11:

1. AG/AB=AE/AD (Use the same strategy as step one in problem 10, since the rectangles are similar we can create this equation)

2. AG/(AG+GB)=AE/(AE+ED) (Rewrite sides as the some of their parts)

3. 14/(14+7)=18/(18+x) (Substitute given values)

4. x=9 (Solve for x)

lmk if there are mistakes in my explanation, hope this helps :)

8 0

3 years ago

What is the 7th number in the pattern: 1, 4, 9, 16, 25, ...

Viefleur [7K]

the answer would be d. 39

8 0

3 years ago

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