What is the radius of a circle given by the equation x2 + y2 – 2x + 8y – 47= 0? radius = units

8 units

Step-by-step explanation:

We need to rewrite an equation in the standard for  a circle form.

r is radius.

(x−h)²+(y−k)²= r²

x² + y² – 2x + 8y – 47= 0

x² - 2x + y² + 8y - 47 = 0

x² - 2*x *1+ 1 ²- 1² + y² + 2*4*y + 4² - 4² - 47 = 0

(x - 1)² + (y + 4)² - 1 - 16 -47 =0

(x - 1)² + (y + 4)² - 64=0

(x - 1)² + (y + 4)² = 8²

Radius is 8.

5x + 3y = - 4

step-by-step explanation:

the equation of a line in standard form is

ax + by = c ( a is a positive integer and b, c are integers )

express the line first of all in slope- intercept form

y = mx + c ( m is the slope and c the y-intercept )

to calculate m use the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (7, - 3) and (x₂, y₂ ) = (4, - 8)

m = = -

y = - x + c ← is the partial equation

to find c substitute either of the 2 points into the partial equation

using (4, - 8 ), then

- 8 = - + c ⇒ c = -

y = - x - ← in slope-intercept form

multiply all terms by 3 to eliminate the fractions

3y = - 5x - 4 ( add 5x to both sides )

5x + 3y = - 4 ← in standard form

b. 18

step-by-step explanation:

so the equation for this is:

ab^2=ac⋅ad

ab being the top length of 6 and ac being the length of 2 and ad being the length of x. let's plug into the equation:

6^2 = 2x

now lets just solve for x:

36 = 2x

18 = x

i hope that !