Solve the system for x:
y = 3x + 1
y = 2x² - 5

Question

Solve the system for x:
y = 3x + 1
y = 2x² - 5

campbell_st · Answer

they are both equal to y so equate the equations 

$$3x + 1 = 2x^2 - 5$$

then rewriting the equation you get

$$2x^2 -3x - 6 = 0$$

the the solution can be found using the general quadratic formula 

$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$

where a = 2, b = -3 and c = -6

hope this helps

anonymous · Answer

So i got (-3 plusorminus sqrt -23)/4

campbell_st · Answer

oops slight numerical error it should be 

$$x = \frac{3 \pm \sqrt{9 + 48}}{4}$$

anonymous · Answer

Oh.
(3 plusorminus sqrt -63)/4

campbell_st · Answer

it looks like 

$$x = \frac{-(-3) \pm \sqrt{(-3)^2 - 4 \times 2 \times -6}}{2 \times 2}$$

squaring a negative gives a positive... so it becomes 

$$x = \frac{3 \pm \sqrt{57}}{4}$$

anonymous · Answer

I'm so off my game today XD

campbell_st · Answer

thats ok... i find the GQF a bit of a pain... 

hope this helps.