can someone help me with x^2+12x+32=0....i think the solution is -4,-8.....please help....?

Question

would i calculate the same for x^2+5x-9=0.......

for x^2+5x-9=0 it could be -5+square root of 61/2......on the right track...???

can someone help me with find the x-intercepts for y=x^2-5x-10 i say....5-square root of 65, and 0......am i almost there

find the axis of symmetry of y=x^2+x+1.......please help.......

x^2+5=21 i know the answer is +4 .........doing pretty good hum........now i just can't seem to get x^2+5-9=0 i know that the answer should be -5+ square root of 61/2...on the right track again hum........

Answer 1

for x^2+5x-9=0 u can't do this the same way.9 * 1 = 9 but 9 + or - 1 not = 5 and 3 * 3 = 9 but 3 + or - 3 not = 5.
so there is a formula u got to use here.
it is x = {- b + - sqrt(b^2 - 4ac)} / { 2a}
so from the given quadratic equation,
a = 1,b = 5 and c = 9
and then u substitute , u will get 2 values of x and that's the answer.remeber we have to use this formula if we are unable to factorise the way u did for the previous one.

Answer 2

The best way to check if your answers are correct is to plug them back into the original equation and see if you get true statements for each.

Checking -4:

(-4)^2 + 12(-4) + 32 ? 0
16 - 48 + 32 ? 0
0 = 0 Yes!

Checking -8:
(-8)^2 + 12(-8) + 32 ? 0
64 - 96 + 32 ? 0
0 = 0 Yes!

Being able to check your own answers isn't just handy -- it's vital. It's likely that in the next chapter in your book, you'll begin solving equations with radicals in them (like square-root-of(x-2) = 5), and sometimes in those problems you can do everything right and still generate false solutions. Therefore, you have to test each answer you get.

Hope that helps!

Answer 3

You are absolutely right!

x^2 + 12x + 32 = 0

two numbers multiplied by each other to get 32 and added together to get 12.

(x + 4) (x + 8) = 0
x = -4 , -8

Answer 4

yes if can be factored to (x+4)(x+8) = 0

so x + 4 = 0 => x = -4
and x + 8 = 0 => = -8
you are correct

Answer 5

The solution is indeed <-4, -8>.

Answer 6

Chikku is spot on when he says that you need to use the formula that he has shown. Without giving the exact answer, if you come up with answers close to 1.4 and minus 6.4 then you've got it right.

Answer 7

x^2 + 12x + 32 = (x + 8)(x + 4), x = -8 or -4

----------------------------

x^2 + 5x - 9 = 0

x = (-b ± sqrt(b^2 - 4ac))/2a
x = (-5 ± sqrt(5^2 - 4(5)(-9)))/(2(1))
x = (-5 ± sqrt(25 + 180))/2
x = (-5 ± sqrt(205))/2
x = (1/2)(-5 ± sqrt(205))

-------------------------------------------

y = x^2 - 5x - 10

x = (-(-5) ± sqrt(25 - 4(1)(-10)))/(2(1))
x = (5 ± sqrt(25 + 40))/2
x = (5 ± sqrt(65))/2
x = (1/2)(5 ± sqrt(65))

------------------------------------------

y = x^2 + x + 1

x = (-b/(2a))
x = -1/(2(1))
x = (-1/2)

AOS = x = (-1/2)

Answer 8

the set of sol. is {-4,-8}

Answer 9

yes