2x^2+7x-5+(-8x^2-3x+5)=-6x^2+4x.
First we get the value of y in terms of x
We have 2x + y + 9 = 0
We transpose 2x and 9 to the other side so we could get the value of y being:
y = - 2x - 9
Now that we have the value of y we can substitute it to the first equation
6x - 3y + 10 = 0
6x - 3 (-2x - 9) + 10 = 0
Simplifying the inside of the parentheses we would have
6x - (3)(-2x) - (3)(-9) + 10 =0
6x + 6x + 27 + 10 = 0
Combining similar terms we would get
12x + 37 = 0
We transpose 37 to the other side for easier simplification
12x = - 37
We divide both sides by 12 to get the value of x
12x/12 = - 37/12
Since 12/12 is equal to 1 our value of x would be
x = - 37/12
Or simply x = - 3.0833
Now that we know the value of x we can use it to obtain the value of y
y = - 2x - 9
y = - 2(-37/12) - 9
y = 37/6 - 9
y = - 17/6
Or in decimal y = - 2.8333
Final values of x and y would be
x = - 3.0833
y = - 2.8333
