factorise

[pliant quarry]

can someone please help real quick, factorise this

how to do it?

apparently this is the answer but idk how to get there

@true hazel could u help please or anyone

[astral girder]

i think this is the difference of 2 squares

when you have two numbers that are squared, you can factorise them like that

like for example

You're told to factorise x^2 - 4

this can be factorised as (x+2)(x-2)

And i think it goes the same to the question you have

because its 7^2

and since x is a variable you just leave it there, hence why the x is there in the answer

[astral girder]

This is just a rule and it only works when the 2 numbers/variables are square numbers and the symbol between them is -

not +

Sorry if this is a bad explaination 😭

[dusty scarab]

erm well you could set 7^x = y

then you would have y^2 - 121

so its a difference of two squares like the person above pointed out

[true hazel]

from index laws

you know that

7^2x = (7^x)^2

so you have [(7^x)^2 - 121]

two square numbers here, 121 and (7^x)^2

diff of 2 squares and it becomes (7^x - 11)(7^x +11)

[pliant quarry]

alr i understand thanks @true hazel @astral girder @dusty scarab