quick question guys, whenever they is a minus outside say for example .. - root 4, would the answer be minus 2?

another question on that, if i have x^0.5 = -2, woul the answer be 4?

Reply 87

Rager6amer

OP

4

Great to see everybody helping each other, really proud of everyone! Good luck tomorrow on core 2 guys, hopefully it will be a decent paper! We can then make an unofficial mark scheme tomorrow

Reply 88

Rager6amer

OP

4

Original post by SunDun111

quick question guys, whenever they is a minus outside say for example .. - root 4, would the answer be minus 2?

another question on that, if i have x^0.5 = -2, woul the answer be 4?

yes that is correct! :smile:

Reply 89

B_9710

18

Original post by SunDun111

quick question guys, whenever they is a minus outside say for example .. - root 4, would the answer be minus 2?

another question on that, if i have x^0.5 = -2, woul the answer be 4?

\sqrt{x} \geq 0

.

\sqrt{x} \neq -2

.
If you graph

y=\sqrt x

then the range is

y \geq 0

.
So

\sqrt x = -2

has no solutions.

Reply 90

HazNut134

5

On the spec for aqa it says that you should use mathematical notation in your working like the 'therefore' symbol. I've been using arrows to show the progression of my working but apparently the arrow means 'implies', so if I use symbols incorrectly but my working is still correct will I be ok?

Reply 91

CrystalPark

In C2 for logarithms how do you manipulate a question with three minus logs??
Coz I know that when there's a minus you divide the logs but how do you do that if there are three minuses??

Ex: log(2)11x+3 - log(2)5x - 2log(2)x = 1
Please help 😭😭😭

Reply 92

SunDun111

11

Original post by B_9710

\sqrt{x} \geq 0

.

\sqrt{x} \neq -2

.
If you graph

y=\sqrt x

then the range is

y \geq 0

.
So

\sqrt x = -2

has no solutions.

kinda confused me haha, so the square root of - 4 (when minus is on the outside) has no solutiosn?

Reply 93

SunDun111

11

Original post by CrystalPark

In C2 for logarithms how do you manipulate a question with three minus logs??
Coz I know that when there's a minus you divide the logs but how do you do that if there are three minuses??

Ex: log(2)11x+3 - log(2)5x - 2log(2)x = 1
Please help 😭😭😭

take one of them to the other side, and turn the 1 into a log, so you get two logs on each side when they are all combines, so the logs cancel.

Reply 94

B_9710

18

Original post by SunDun111

kinda confused me haha, so the square root of - 4 (when minus is on the outside) has no solutiosn?

That's not quite what i'm saying.

-\sqrt 4 =-2

and that's perfectly well defined.

\sqrt{-4} =2i

which of course is not a real number. However you simply cannot have

\sqrt x =-2

. You can square both sides and get x=4, but putting x=4 into the square root returns 2, not -2. Taking the square root of a number never gives you a negative number.