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What are the solutions to the following system of equations?
y = x² + 7x - 5
2x - y = -9

1 Answer

11 votes

Answer:

x= -7, y= -5 and

x= 2, y= 13

This may also be written as (-7, -5) and (2, 13).

Explanation:

Start by labelling the two given equations:

y= x² +7x -5 -----(1)

2x -y= -9 -----(2)

Let's solve by substitution!

Making y the subject of formula in equation (2):

From (2): y= 2x +9 -----(3)

Substitute (3) into (1):

2x +9= x² +7x -5

x² +7x -5 -2x -9= 0

x² +5x -14= 0

Factorise:

(x +7)(x -2)= 0

x +7= 0 or x -2= 0

x= -7 or x= 2

Find the respective values of y.

Substitute into (1):

y= (-7)² +7(-7) -5 or y= (2)² +7(2) -5

y= 49 -49 -5 or y= 4 +14 -5

y= -5 or y= 13

Thus, the solutions are (-7, -5) and (2, 13).

What are the solutions to the following system of equations? y = x² + 7x - 5 2x - y-example-1
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