Solution for Exercise 2.88

[lightningbolts]

function negate_term(t) {
  let new_num = -tail(coeff(t))
  return make_term(order(t), make_javascript_number(new_num))
}

function negate_poly(p) {
  return tail(make_polynomial("x", map(negate_term, tail(p))))
}

function sub_poly(p1, p2) {
  return add_poly(p1, negate_poly(p2))
}
const p1 = make_polynomial("x",
      list(make_term(2, make_javascript_number(4)),
        make_term(1, make_javascript_number(3)),
        make_term(0, make_javascript_number(7))));
const p2 = make_polynomial("x",
      list(make_term(2, make_javascript_number(5)),
        make_term(1, make_javascript_number(2)),
        make_term(0, make_javascript_number(10))));
sub(p1, p2)
/*Result is
make_polynomial("x",
      list(make_term(2, make_javascript_number(-1)),
        make_term(1, make_javascript_number(1)),
        make_term(0, make_javascript_number(-3))))
*/