What is the variable in the expression 9c-4

Mathematics

2 answers:

nexus9112 [7]3 years ago

6 0

Answer:

Variable is C

Step-by-step explanation:

____ [38]3 years ago

5 0

Answer:

The variable in the expression is 'c'.

Step-by-step explanation:

A variable is a letter that we use to represent a number that changes. "c" is the only letter in the expression, so its the variable.

We use variables when we do not know what the number should be, or when it's unknown.

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The first one how to do it I’m confused

Aliun [14]

She has $900 total in her account.

she needs to get the laptop, that's $600 in costs.

and she pulls out $60 for food, how many times can she do that?

the first time she pulls them out, the amount is 60,

the second time she does it, the amount will have been 60 + 60 or 60(2),

the third time she does it again, the amount withdrawn will be 60(3)

the fourth time of the withdrawal the amount pulled out will be 60(4)

now, if she does "f" times for food, the "f" time she does it, the amount withdrawn would be 60(f) or just 60f.

now, we know the laptop costs $600, and her food withdrawals are 60f, she's not putting anything in the account, so the 900 bucks are just shrinking with every withdrawal for either laptop or food.

so, her expenses are, the laptop and food, 600 + 60f.

whatever "f" may be, that amount must never be greater than 900, because that's all she has in the account, and if she uses more the bank will let the dobermans loose on her.

so, 600 + 60f must be "less than or equals to" 900.

900 ⩾ 600 + 60f

now, how many times can she withdraw? what's "f"?

$\bf 900 \ge 600 + 60f\implies 300\ge 60f\implies \cfrac{300}{60}\ge f\implies 5\ge f$

6 0

3 years ago

What is the probability of rolling a number less than six on a number cube?

Kipish [7]

Likely

There are six outcomes 1, 2, 3, 4, 5, and 6
Numbers less than 6, are 1, 2, 3, 4, and 5, so the chance to roll a number less than 6 is 5/6 which has a probability of likely as there are more chances to roll a number less than six

6 0

2 years ago

Read 2 more answers

Determine the next step for solving the quadratic equation by completing the square.

nexus9112 [7]

$\qquad \textit{perfect square trinomial} \\\\ (a\pm b)^2\implies a^2\pm \stackrel{\stackrel{\text{\small 2}\cdot \sqrt{\textit{\small a}^2}\cdot \sqrt{\textit{\small b}^2}}{\downarrow }}{2ab} + b^2$

the idea behind the completion of the square is simply using a perfect square trinomial, hmmm usually we do that by using our very good friend Mr Zero, 0.

if we look at the 2nd step, we have a group as x² - x, hmmm so we need a third element, which will be squared.

keeping in mind that the middle term of the perfect square trinomial is simply the product of the roots of "a" and "b", so in this case the middle term is "-x", and the 1st term is x², so we can say that

$\stackrel{middle~term}{2(\sqrt{x^2})(\sqrt{b^2})~}~ = ~~\stackrel{middle~term}{-x}\implies 2xb~~ = ~~~~ = ~~-x \\\\\\ b=\cfrac{-x}{2x} \implies b=-\cfrac{1}{2}$

so that means that our missing third term for a perfect square trinomial is simply 1/2, now we'll go to our good friend Mr Zero, if we add (1/2)², we have to also subtract (1/2)², because all we're really doing is borrowing from Zero, so we'll be including then +(1/2)² and -(1/2)², keeping in mind that 1/4 - 1/4 = 0, so let's do that.

$-3~~ = ~~-2\left[ x^2-x+\left( \cfrac{1}{2} \right)^2 ~~ - ~~\left( \cfrac{1}{2} \right)^2\right]\implies -3=-2\left(x^2-x+\cfrac{1}{4}-\cfrac{1}{4} \right) \\\\\\ -3=-2\left(x^2-x+\cfrac{1}{4} \right)+(-2)-\cfrac{1}{4}\implies -3=-2\left(x^2-x+\cfrac{1}{4} \right)+\cfrac{1}{2} \\\\\\ -3-\cfrac{1}{2}=-2\left(x^2-x+\cfrac{1}{4} \right)\implies -\cfrac{7}{2}=-2\left(x-\cfrac{1}{2} \right)^2\implies \cfrac{7}{4}=\left(x-\cfrac{1}{2} \right)^2$

$~\dotfill\\\\ \pm\sqrt{\cfrac{7}{4}}=x-\cfrac{1}{2}\implies \cfrac{\pm\sqrt{7}}{2}=x-\cfrac{1}{2}\implies \cfrac{\pm\sqrt{7}}{2}+\cfrac{1}{2}=x \implies \cfrac{\pm\sqrt{7}+1}{2}=x$