Why i can not save many posts

 _ +  _ +  _ = 30 (Fill the blank by using numbers 1, 3, 5, 7, 9, 11, 13, 15)

u can also repeat the no.also

In ABC, AD perpendicular to BC. Prove that AB² - BD² = AC² - CD²? 

How many terms of the Arithmetic Progression 9, 17, 25....must be taken to get a sum of 450?

Can I calculate  all areas first  and foremost total area of 13.1 7th question 

Without expanding prove that determinant

     b² c².       bc.          b+c

     c² a².       ca.          c+a

     a² b².        ab.         a+b

sir/mam this is a question4 of maths class 11 ch-10 miscellaneous exercise. Can you please tell me why my answer is not coming? And where am I going wrong in this?

• Sir can u give me another solution of class 12th chapter 7 and exercise 7.4 question number 15 in another way I can not understand this solution of questions number 15 please give another way of this question thanks and have a nice day
  

Find dy/dx if y= log(-sinx)/(+sinx)

How to draw graph with two variables

What is the formula to calculate the sum of the series