Question

Help please!!!

Which of the following is a solution of x2 - 7x = -5?

7 plus or minus the square root of 69 divided by two

7 plus or minus the square root of 29 divided by two.

negative 7 plus or minus the square root of 29 divided by two

negative 7 plus or minus the square root of 69 divided by two.

Answer 1

do you know quadratic formula ?

Answer 2

Yes, b+/-sqrt(b^2-2ac)/2a

Answer 3

so, we have
x^2 - 7x +5 = 0
can you find a,b,c ?

Answer 4

It's C, right?

Answer 5

i didn't work out yet, did you work it out ?

Answer 6

because, it would be

-7+/-sqrt(-7^2-2(1)(-5))/2(1)

Answer 7

first of all,
b = -7
so, -b = +7

Answer 8

so its not C or D

Answer 9

Riiighhht, I forgot about that part, damn. I think I have the formula wrong then.

Answer 10

Compare your quadratic equation with \(ax^2+bx+c=0\)
find \[a=...?\\b=...?\\c=...?\\\] \[ \\ \sqrt{b^2-4ac}=...?\]
then the two roots of x are:
\(\huge{x_{1,2}=\frac{-b \pm \sqrt{b^2-4ac}}{2a}}\)

Answer 11

Okay, i've got it! It's 7+/-sqrt(29)/2 so the answer is B!

Answer 12

b = -7
a = 1
c = 5

b^2 - 4ac = 49 - 20 = 29
yes, you're correct :)

Answer 13

Can you help me with another one if possible(?)

Answer 14

sure

Answer 15

I already know it's not A. But, I don't know which one of the other 3 it could be.

Solve x2 + 6x + 7 = 0.

x = -1 and x = -5

3 plus or minus square root of 2

negative 3 plus or minus square root of 2

quantity of negative 3 plus or minus square root of 2 all over 2

Answer 16

what values of a,b,c you got ?

Answer 17

1, 6 and 7.

Answer 18

yes
b^2 -4ac =....

Answer 19

6^2-4(1)(7)

36-28
8

Answer 20

good,
so where are you stuck ??
proceed

Answer 21

[-6 +/- sqrt 8 ] /2
got this ?

Answer 22

Yeah. But then what, how does it end up like that?

Answer 23

-6/2 +/- (sqrt 8)/2

so you need to simplify sqrt 8

can you factor 8 ?

Answer 24

There's 4 and 2.

Answer 25

good!
\(\sqrt 8 = \sqrt 4 \sqrt 2\)
whats sqrt 4 ??

Answer 26

2

Answer 27

so it would go as 2sqrt(2)

Answer 28

yes

Answer 29

-6/2 +/- (sqrt 8)/2

=-6/2 +/- ( 2 sqrt 2)/2

simplify ?

Answer 30

(-3+/-(2sqrt2))/2 so iiiittsss D!

Answer 31

=-6/2 +/- ( 2 sqrt 2)/2

= -3 +/- sqrt 2

the '2' gets cancelled from numerator and denominator for BOTH the terms

Answer 32

doubts ?

Answer 33

So it just ends up just being C?

Answer 34

yes.

Answer 35

Thank you sooo much!!!

Answer 36

welcome ^_^