1) When a quantity (variable n) in an equation is not know and you are trying to evaluate it. For example, if a banana costs 5 cents, how many can you buy for 25 cents. We solve this by saying
Let n be the number of bananas that we can buy for 25 cents, then we have
5 x n = 25 and hence n = (25/5) = 5
2) When you want to express the general term in a series. For example the arithmetic series 1, 4, 7, 10, 13, 16,.......... is really
1, (1+3), (1+6), (1+9), (1+12), (1+15).......... and in general for such an arithmetic series you can find the 100th, 223rd, 567th term without writing down the long chain of numbers. How? we see a pattern in the arithmetic series. If we represent the starting number (1 in our case) as "a"and the equal increment from one term to the next (that's how an aritmetic series is defined) as "r" then the formlua "a + (n-1)r" gives you the n-th number. Remember that in the illustration above 1 is considered the 1st term in the series, (1+3) is the2nd term, (1+6) is the3rd term and so on.
In this case, you'll have to use a variable. Variables are basically a symbol which stands for a number. Let's use the variable "m". You're searching for 58 less than a number. That is basically just "word form" for a number, or a variable, minus 58. So if we use the variable "m", the expression will be m-58. Remember that you can use any variable you want.
when ther is no number
it is the number you would use to solve the problem
x + 138
Subtract 25 from whatever variable you use for "a number". If your number is "x", then the expression becomes "x - 25".
(x + 9)
Assuming you call your number "n", the expression would be "14n". You can replace "n" with whatever variable you want to use.
Translate the following phrase into a variable expression. Use the letter d to name the variable. …7 times the distance
A variable is a letter that represents a number. An expression that contains at least one variable is called variable expression, also called algebraic expression. A variable expression has one or more terms. A term is a number, a variable, or a product of numbers and variables. For example,3(x^2)y + 2xy + x - 7 is a variable expression, where you have 4 terms.When working with variable expression, you often use the substitution principle:If a = b, then a may be replaced by b in any expression.The set of numbers that a variable may be represent is called replacement set, or domain, of the variable. To evaluate a variable expression, you replace each variable with one of its values and simplify the numerical expression that results.Example: Evaluate the expression 2x - 4y for x = 5 and y = -9.Solution:2x - 4y= 2(5) - 4(-9)= 10 + 36=46
that we can use it
Roman numerals use letters in place of numbers. An unknown variable in algebra uses a letter instead of a number.
we will use the variable 's' to represent your savings: 2s+10
Anywhere you want. In general, you can use a variable anywhere you can use a number.
Instead of using W as a variable in your model, you use log(W).
Basically, an expression is not a polynomial when anything is done that is not allowed in a polynomial - for example, use any variable in the denominator of a monomial, use non-integral powers or radicals (which is basically the same as a non-integral power), use functions, etc.
Let n = the original number n + 8 = another number which is 8 more than the original number Therefore, the two variable expressions are n and n+8