Write the first term and the difference of the arithmetic progression if a 3 = 25, and 10 = -3

Let us find out what value the difference will be equal to, when we know for sure from the condition of the task that the term of the progression numbered 3 is 25, and the term of the progression numbered 10 is -3:

d = -3 – 25: (10 – 3) = -28: 7 = -4.

Let’s find out what number is in first place in the specified progression under the specified conditions:

a1 = a3 – 2d = 25 – 2 * (-4) = 33.

Answer: The number 33 is in the first place in the indicated progression, and its difference is -4.