Find the solution of the system of equations -7x-3y=-20 3x+6y=-15

9514 1404 393

  (5, -5)

Step-by-step explanation:

I like a graphing calculator for quickly finding a solution to a system of equations. It shows the solution to be (5, -5).

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We can add the second equation to 2 times the first to eliminate the y-variable.

  2(-7x -3y) +(3x +6y) = 2(-20) +(-15)

  -11x = -55 . . . . . collect terms

  x = 5 . . . . . . . . . divide by -11

Substituting this value into the second equation, we have ...

  3(5) +6y = -15

  6y = -30 . . . . . . . . subtract 15

  y = -5 . . . . . . . . . . divide by 6

The solution is (x, y) = (5, -5).

i think is g(1)=-1.

hope that i can

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional