Question

9 3x·(7·x)

Explanation:

Step1: Use associative property of multiplication

The associative property of multiplication states that \( (a \cdot b) \cdot c = a \cdot (b \cdot c) \). So we can remove the parentheses and re - order the factors: \( 3x\cdot(7\cdot x)=(3x\cdot7)\cdot x = 3\cdot7\cdot x\cdot x\)

Step2: Multiply the coefficients and the variables

Multiply the coefficients \( 3\times7 = 21\). For the variables, when we multiply \( x\cdot x\), using the rule of exponents \( a^m\cdot a^n=a^{m + n}\), here \( m = 1\) and \( n = 1\), so \( x\cdot x=x^{1+1}=x^{2}\)

Step3: Combine the results

Combine the coefficient and the variable part: \( 3\cdot7\cdot x\cdot x = 21x^{2}\)

Answer:

\(21x^{2}\)