1.) 1.47 x 10^4 is the correct answer
Answer:
Infinite number of rational numbers exist between any two distinct rational numbers. We know that a rational number is a number which can be written in the form of qp where p and q are integers and q =0.
5x²+13x-4-17x²-7x+19+15x²+5x-21x-7=
=5x²+15x²-17x² +(13x-7x+5x-21x) -4-7+19=
=3x²-10x+8