Can someone please help me? Describe the mistake in solving for x. Then, redo the question correctly.​

What is the common difference in the following arithmetic sequence 7,3,-1,-5

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Prove the converse of the pythagorean theorem using similar triangles. the converse of the pythagorean theorem states that when the sum of the squares of the lengths of the legs of the triangle equals the squares length of the hypotenuse, the triangle is a right triangle. be sure to create and name the appropriate geometric figures.