What is the radius of the circle x2 + y2 -1=0?

1

Step-by-step explanation:

rewrite x^2 + y^2 -1 = 0 as x^2 + y^2 = 1

the 1 on the right hand side of the equation is equal to the radius squared

1 = r^2

r = 1

radius = 1

Step-by-step explanation:

x^2 + y^2 -1=0

Add 1 to each side

x^2 + y^2 -1+1=0+1

x^2+y^2 = 1

This is written in the form

(x-h)^2 + (y-k)^2 = 1^2  where (h,k) is the center and r is the radius

The center is (0,0) and the radius is 1

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places

step-by-step explanation: