What is the solution to the system of equations below?

y = -5x - 1
4x - 7y = 7

Hi

When you have a system of equation, you generally have two unknowned value.  

The trick is to express one letter as equal of something in the second letter.

We have two lines :  

(1) :  y = -5x-1

(2) :  4x-7y = 7

Here as the job is donne as  we have :   y = -5x-1  

So I can rewrite line (2)  as this  :   4x-7y = 7

                                                         4x - 7 ( -5x-1) = 7

                                                           4x-7 * (-5x) - 7* (-1) = 7

                                                            4x +35x +7 = 7

                                                             4x +35x +7 -7 = 7-7

                                                             39x = 0

                                                                  39x/39 = 0 /39

                                                                      x = 0

So if X = 0  then we have in line (1)  we have by replacing  "x" by it's value :    y = -5*0 -1  

y =  -1

Dont hesitate to ask in comments if it's still not clear.

circle area = pi * radius^2

if diameter = 10 then radius = 5

circle area = pi * 5^2

circle area = pi * 25

circle area = 78.5398163397 square units

step-by-step explanation: