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ESO Y4A · Mathematics
Algebra · Polynomials

Monomials

The number of "likes" a post gains in a week could be modelled with a monomial such as $-\frac{3}{5}x^2y^3z$. You already know how to read monomials from 2nd and 3rd ESO; here we review quickly and add letters and slightly more complicated coefficients.

Before you start, make sure you know: Monomials (2nd ESO)
Before you start, make sure you know: The language of algebra (2nd ESO)

Coefficient, literal part and degree

Breakdown of the monomial −3/5 x²y³z identifying the coefficient, the literal part and the sum of the exponents to calculate the degree 6. −3/5 x²y³z coefficientliteral part degree = 2 + 3 + 1 = 6 (the z has exponent 1, even if it is not written)
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Identify the coefficient, the variable part and the degree of the monomial $-\frac{3}{5}x^2y^3z$.

Identify the coefficient, the variable part and the degree of the monomial $-\frac{3}{5}x^2y^3z$.

Solve

Like monomials

$5x^2y$ and $-2yx^2$ are like monomials (the order of the letters does not matter). $5x^2y$ and $5xy^2$ are not: the exponents do not match letter by letter.

Comparison of two like monomials showing that they share exactly the same literal part with the same exponents despite having different coefficients. like monomials 5x²y −2yx² not like monomials 5x²y 5xy² (crossed exponents)
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Check whether the monomials $A = 5x^2y$ and $B = -2yx^2$ are like terms. If so, calculate their sum $A + B$ and their difference $A - B$.

Check whether the monomials $A = 5x^2y$ and $B = -2yx^2$ are like terms. If so, calculate their sum $A + B$ and their difference $A - B$.

Solve

Numerical value

To calculate the numerical value of a monomial with several letters, substitute each letter with its value (in brackets if it is negative) and calculate.

Calculation of the numerical value of the monomial 4x²y³ for x = −2 and y = 3 by substituting the variables and working out the powers before the final product. M(x,y) = 4x²y³ x = −2(−2)² = 4 y = 33³ = 27 4 · 4 · 27 = 432
Practice★☆☆Not started
Find the numerical value of the monomial $M(x,y) = 4x^2y^3$ for the values $x = -2$ and $y = 3$.

Find the numerical value of the monomial $M(x,y) = 4x^2y^3$ for the values $x = -2$ and $y = 3$.

Solve

Translating sentences into a monomial

Many problems describe a monomial in words. You translate "from the inside out": first what is closest to each number, then the rest.

Step-by-step diagram translating a sentence in everyday language into a monomial with several variables and their corresponding exponents. "half the product of the squareof a and the cube of b" 1/2 · a² · b³ = ½a²b³
Practice★☆☆Not started
Write the monomial that mathematically represents the following statement: "Half the product of the square of a number and the cube of a different number".

Write the monomial that mathematically represents the following statement: "Half the product of the square of a number and the cube of a different number".

Solve

Summary

See all the exercises in this section