Substitution method
x-y=9
x+y=7

(8, - 1 )

Step-by-step explanation:

Given the 2 equations

x - y = 9 → (1)

x + y = 7 → (2)

Rearrange (1) expressing x in terms of y by adding y to both sides

x = 9 + y → (3)

Substitute x = 9 + y into (2)

9 + y + y = 7

9 + 2y = 7 ( subtract 9 from both sides )

2y = - 2 ( divide both sides by 2 )

y = - 1

Substitute y = - 1 into (3) for corresponding value of x

x = 9 - 1 = 8

Solution is (8, - 1 )

salary

step-by-step explanation:

let's call the solutions x₁ = (5 - 2√7)/3 and x₂ = (5 + 2√7)/3

then the equation is (x-x₁)(x-x₂) = 0

if you fill that in you get a lot of numbers which you can recognize as ax²+bx+c=0.

step-by-step explanation:

you can see that a=1 (there is just an x²)

b = (-5 -2√7 + 2√7 - 5)/3 = -10/3

c = -2√7)/3 ) * (-5+2√7)/3) = -1/3

so your answer is 3x^2 – 10x – 1 = 0