Question 843458
The second question: Interpreting the question
{{{4 * 4th=7 * 7th}}}{{{4*(a+ 3d)=7*(a+ 7d}}}{{{4a+ 12d=7a+ 49d}}}
collect like terms{{{4a-7a=49d-12d}}}{{{-3a=30d}}} divide both sides by -3, then {{{a=-10d}}}. Now {{{11th=a+ 10d}}}substitute a=-10d, then {{{11th=-10d + 10d}}}. Therefore {{{11th=0}}}