(2.5×10−8)(9×10−10)

express your answer in scientific notation.

2.25x

Scientific notation is used in science because the number can be vary from so much that using decimal is making it hard. The number expressed in  form. Both number in the question is already in scientific notation. Then to multiply the number and keep it at scienfitic notation the calculation should be:

2.5 x x 9 x = 22.5 x = 2.25x

We have given expression as



Now we can multiply 2.5 and 9 and also combine exponents of 10.


                                                  = 

Now for writing it into scientific notation we have to shift decimal by one place in backward direction.
So we can write answer as



So answer is 

Y=-2x-6 is the answer