What was the purpose of the coordinate graphing system described by descartes in his book discourse on method?

a. to use algebraic methods to solve geometric problems.
b. to prove the universe was sun-centered.
c. to represent equations for the queen of sweden.
d. to prove his own existence.

A. To use algebraic methods to solve geometric problems.

Step-by-step explanation:

Descartes, a French mathematician and a philosopher, explained what is  the system of Cartesian Coordinates. In Descartes's system of coordinates, geometry and algebra were united for the first time to create which known as analytic geometry .

Cartesian coordinates are used to plot a point in expanse by giving its respective distance from perpendicular intersecting lines named as x axis and y axis. In coordinate geometry all points, lines, and figures can be drawn in a coordinate plane by references of both the axes.

it is a. 4.2 because 7.6-3.4 gets the remaining length of 4.2. i might be wrong but i am pretty sure this is the answer.

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.