SOLUTION: work out the solutions to these simultaneous equations: y = 2x y = x^2 - 8

Algebra.Com
Question 1207780: work out the solutions to these simultaneous equations:
y = 2x
y = x^2 - 8
Answer by ikleyn(52778)   (Show Source): You can put this solution on YOUR website!
.
work out the solutions to these simultaneous equations:
y = 2x
y = x^2 - 8
~~~~~~~~~~~~~~~~~~~~ 

Left sides are identical - hence, right sides are equal

    2x = x^2 - 8,

or

    x^2 - 2x - 8 = 0,

Factor left side

    (x-4)(x+2) = 0.


One solution is  x = 4;  y = 2x = 8.       CHECK:  x^2-8 = 4^2-8 = 8.       <<<---=== correct .

Another solution is x = -2;  y = 2x = -4.  CHECK:  x^2-8 = (-2)^2-8 = -4.   <<<---=== correct .

Solved.



RELATED QUESTIONS

a) Graph the equations y=-x^2+3x+8 & y=2x+6 (find suitable coordinates to plot) b) Use... (answered by josgarithmetic)
Please solve these simultaneous equations: y=x+2... (answered by ankor@dixie-net.com)
can you please explain how you work these out. i would be gratful if you show your... (answered by stanbon)
Show that the X solutions of the simultaneous equations Y = X - 2 xy = 3 Are... (answered by jim_thompson5910)
please show me step by step how to solve these simultaneous equations using the... (answered by ramkikk66)
Solve the simultaneous equations:... (answered by Cromlix)
Solve the simultaneous equations y = |x - 5| and y = |3 - 2x| +... (answered by josgarithmetic)
Solve the simultaneous equations y = | x-5 | and y = | 3-2x | +... (answered by greenestamps)
esay question: solve the simultaneous equations. y=7x+11 and... (answered by josgarithmetic)