Solve the equation.
square root of 5x+1=6
square root of x-2 +7=-4
x2+7x+4=0
5x2=-15

Question

anonymous · Answer

1) x=7
2) x=123
3) x=-6.37, -.63
4) x=9

anonymous · Answer

how did u get these answers

radar · Answer

Would like to see how the answer to the 4th one was developed.  when 9 is substitued in the equation:
$$5(9)^{2}=-15$$
$$(9)^{2}=-15/5=-3$$
$$81\neq-3$$

anonymous · Answer

Yeah, my bad I read it wrong. It's actually 3i.

radar · Answer

Gettin there...... how about $$i \sqrt{3}$$

anonymous · Answer

$$5x ^{2}= -15$$
$$X ^{2}= -15\div5=-3$$
$$X=\sqrt{-3}$$
$$X= i \sqrt{3}$$

anonymous · Answer

Sorry about that, I'm new to this and I hadn't yet figured out the equation inserts.

radar · Answer

What method did you use on number 3.  Did you use quadratic formula?

anonymous · Answer

Yes. First I put it in the equation and solved, simplifying tona decimal and rounding to the nearest hundredth.

I also checked the zeroes on the graph.

anonymous · Answer

5x^2 = -15
x^2 = -3    take the square root

x = +- i sqrt(3)

radar · Answer

Very good. lerachia is there any more questions?

radar · Answer

blexting thanks , so their is two answers for number 4
$$i \sqrt{3}$$$$-i \sqrt{3}$$

radar · Answer

lerachia, do you understand how quantum torch got those answers or do you care?

anonymous · Answer

Yes, when you move an even power (either the numerator or denominator) there are multiple answers. I don't know how to write that with the equation thing yet though, but the rule applies, so thanks on my part as well.

radar · Answer

good night all.