year 8 maths question...help!?

Question

This is one of my daughters maths homework questions....I can't fathom it....
x squared + 49 = 0


ermmm......help!

Answer 1

my brother also had this question you are not yet supposed to be dealing with complex numbers so the answer you give is there is no answer. got my brother full marks

Answer 2

You need to work backwards:

0 - 49 = -49, though the next step would be to find the square root of -49, and this is not possible, since squaring a negative number will give a positive answer.

I think there is something wrong with the question personally!

Answer 3

i dont agree with all the answers if you take the number negative seven and square it the result is +49

the one where the terms are factored (x-7) times (x-7), if you take these two terms and multiply them by each other you get (x^2)-7x-7x+49 which combines to form (x^2)-14x+49 and there is originally no plain x term in your equation.

are you sure you wrote the original equation down correctly i am thinking it should be xsquared-49=0 in that case x would have a value of positive or negative 7 since squaring either one of those would yield +49 and then you would subtract 49 because of the original equation and your result is zero, so please check the eqn.

by the way i am assuming that 8th grade doesn't delve into imaginary numbers which is the only way to present the solution to the equation you presented above.

Answer 4

Reading the question, I think the Xsquared part of the question must be a negative number. The only number to match the criterion must only be -7x 7 which will equal -49. Then add 49 to this answer to get 0 (zero). i.e -7 x 7 = -49 + 49 = 0. I think this is right. maybe if it is wrong someone will put you on the right path. Hope this helps.

Answer 5

X squared must equal minus 49 therefore X = +7 and -7,otherwise the question does not make sense. Note- the only way you can get minus 49 is to multiply +7 by-7. A minus number multiplied by a minus number always gives a positive number.

Answer 6

7i

You would subtract 49 from both sides so it would be X (squared) = -49

the square root of 49 is 7, but -7 x -7= 49 and there's no way to make it -49, so you have to dive into imaginary numbers (hence the i)

Now, the number i is defined to be equal to the square root of -1.
This means that i^2 (i squared) is equal to -1. So now we can find
the square root of -49.

Since -49 = (-1) 49, we can write:

sqr(-49) = sqr(-1) times sqr(49) (property of square roots)
sqr(-49) = i times 7

This is usually written as 7i. We can check by squaring 7i. We get 7 x 7 = 49 times i x i = sqr(-1) times sqr(-1) = -1, giving 49 times
-1 or -49.

Answer 7

This is a simple but unusual quadratic. All you can do with it is that 49 is the square root of 7 so the answer would be
(x+7) (x-7)

From factorising it is therefore
x = -7 x = 7

Or (for some reason i got two answers)

Do a flow chart and work backwards and i got x = -7

Answer 8

I,m guessing you meant 8th grade 1) 2/5 as a decimal is 0.4 as a percentage it's 40% 2) 0.1 as a Fraction is 1/10 as percentage 10% 3) 25% as a fraction is 1/4 as decimal 0.25 4)7/20 as a decimal is 0.35 and as a percentage 35% 5) 0.625 as a fraction 5/8 and as a percentage 62.5% 6) 12% as a fraction 3/25 and as a decimal 0.12 You could have done this on your calculator and saved some points

Answer 9

If your daughter is solving equations with imaginary or complex roots, then this is OK. If not, something is amiss.
x^2 + 49 can be written x^2 - 49i^2 where i is sqrt(-1).
As the difference of two squares, this can be factorised:
(x-7i)(x+7i) = 0
Equating each of the factors in turn to 0:
x = 7i or x = -7i.

Answer 10

x is minus 7.
-7 x -7 is -49. Plus 49 = 0

Answer 11

you start by subtracting 49 from each side to get
x squared=-49
then you take the square root of each side
you are left with x=the square root of -49
since there is no square root of that you change it to
x=square root of 49 x square root of -1
the root of 49 is seven and the square root of -1 is also known as i

the answer is

x=7i