(x-5y-3x) (x+25y⅔+9z2+5xy-15yz+3xz)
Answers
Answer:
The answer is 39
Step-by-step explanation
We now know very well what a variable is. We use letters x, y, l, m, ... etc. to denote variables. A variable can take various values. Its value is not fixed. On the other hand, a constant has a fixed value. Examples of constants are: 4, 100, –17, etc.
We combine variables and constants to make algebraic expressions. For this, we use the operations of addition, subtraction, multiplication and division. We have already come across expressions like 4x + 5, 10y – 20. The expression 4x + 5 is obtained from the variable x, first by multiplying x by the constant 4 and then adding the constant 5 to the product. Similarly, 10y – 20 is obtained by first multiplying y by 10 and then subtracting 20 from the product.
The above expressions were obtained by combining variables with constants. We can also obtain expressions by combining variables with themselves or with other variables. Look at how the following expressions are obtained:
x2, 2y2, 3x2 – 5, xy, 4xy + 7
(i) The expression x2 is obtained by multiplying the variable x by itself;
x × x = x2
Just as 4 × 4 is written as 42, we write x × x = x2. It is commonly read as x squared.
(Later, when you study the chapter ‘Exponents and Powers’ you will realise that x2
may also be read as x raised to the power 2).
In the same manner, we can write x × x × x = x3
Commonly, x3 is read as ‘x cubed’. Later, you will realise that x3 may also be read
as x raised to the power 3.
x, x2, x3, ... are all algebraic expressions obtained from