Question

answer this question​

Answer 1

Answer:

$if \: 7 +3x \: is \: a \: factor \: of \: {3x}^{3} + 7x \\ then \: 7 + 3x = 0 \\ 3x = - 7 \\ x = - \frac{7}{3} \\ substituting \: the \: value \: of \: x = \frac{ - 7}{3} \: in \: question$

${3x}^{3} + 7x = 0\\ 3 \times { (\frac{ - 7}{3}) }^{3} + 7 \times \frac{ - 7}{3} = 0 \\ 3 \times \frac{ - 343}{27} - \frac{49}{3} = 0 \\ \frac{ - 343}{9} - \frac{49}{3} = 0 \\ \frac{ - 343 - 49 \times 3}{9} = 0 \\ \frac{ - 343 - 147}{9} = 0 \\ \frac{ - 490}{9} = 0$

L. H. S. does not equal to RHS

so, 7 +3x is not the factor of 3x cube +7x