Given ab||dc, ad||bc, ab=cd, ad=cb prove: abd=cdb

Tracy solved the following problem. which of the statements is true? 9 ÷ 3 + 6 × 2 3 + 6 × 2 9 × 2 18 her answer is correct. her answer is incorrect. she should have multiplied before dividing. her answer is incorrect. she should have multiplied before adding. her answer is incorrect. she should have added before dividing.

Find the maximum value of p= 4x + 5y subject to the following constraints :

State one method by which you can recognize a perfect square trinomial.