Question

Solve the simultaneous equation: y=2x²+3x-31 y= x= 21-2x​

Answer 1

Answer:

1. x =(3-√257)/4=-3.258

2. x =(3+√257)/4= 4.758

Step-by-step explanation:

irst add  

x

to both sides of the second equation to get:

y = x + 3

Then substitute this expression for  y  into the first equation to get:

29 = x 2 + ( x + 3 ) 2 = 2 x 2 + 6 x + 9

Subtract  29  from both ends to get:

0 = 2 x 2 + 6 x − 20

Divide both sides by  2  to get:

0 = x 2 + 3 x− 10 = ( x+ 5 ) ( x − 2 )  

So  x = 2 or  x = − 5

If  x = 2  then  y = x + 3 = 5 .

If  x = − 5  then  y=x + 3 = − 2

So the two solutions  

( x, y )  are  ( 2 , 5 )  and  ( − 5 , − 2 )