Question

Choose the correct simplification of 7x2(6x + 3x2 − 4). 21x4 − 42x3 + 28x2 42x4 + 21x3 − 3x2 21x4 + 42x3 − 28x2 42x4 − 13x3 + 11x2

Answer 1

7x²(6x + 3x² - 4)

7x² × 6x = 42x³

7x² × 3x² = 21x⁴

7x² × -4 = -28x²

42x³ + 21x⁴ - 28x² is the correct answer.

Answer 2

Option (3) is correct.

`7x^2(6x+3x^2-4)=21x^4+42x^3-28x^2`

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.