Answer:
Option (3) is correct.
\(7x^2(6x+3x^2-4)=21x^4+42x^3-28x^2\)
Step-by-step explanation:
Given: expression \(7x^2(6x+3x^2-4)\)
We have to write the correct simplification of the given expression \(7x^2(6x+3x^2-4)\)
Consider the given expression \(7x^2(6x+3x^2-4)\)
Multiply \(7x^2\) with each term in brackets \((6x+3x^2-4)\)
we get,
\(=7x^2\cdot \:6x+7x^2\cdot \:3x^2+7x^2\left(-4\right)\)
Apply exponent rule, \(a^b\cdot \:a^c=a^{b+c}\) and Simplify by multiply, we get,
\(=42x^3+21x^4-28x^2\)
Thus, Rearranging in standard form, we get,
\(=21x^4+42x^3-28x^2\)
Thus, Option (3) is correct.
