Question

3r^2-3r-270

Answer 1

Question is?

Answer 2

i have to factor it

Answer 3

we can take out a common factor, what number do u think all the terms in your equation are a factor of? (i.e what number can each term be divided by)

Answer 4

my teacher gave me the answer which is 3(r+9)(r-10) but we have to show our work to show that we know how to do it and honestly I always have trouble with these

Answer 5

yes can u see that there is a 3 outside both brackets? that means in the equation 3r^2-3r-270, each term can be divided by 3... now if each term can be divided by 3, lets see what the next step of the equation will look like. ill start u off ...
3r^2-3r-270
3(r^2-r ..... what will be next

Answer 6

90

Answer 7

good. now the equation look like this
3r^2-3r-270
take 3 as the common factor out.
3(r^2-r-90)

Answer 8

now we need to factorise inside the bracket... can u think of two numbers that will multiply to -90 and add to -1

Answer 9

1?

Answer 10

i need two numbers... that will multiply to -90 and add to -1

Answer 11

1 and -1

Answer 12

hmm both numbers need to multiply to -90

Answer 13

but also add to -1

Answer 14

9 and -10?

Answer 15

YES :D

Answer 16

all u need to do now is write them as such

3r^2-3r-270
take 3 as the common factor out.
3(r^2-r-90)
now to factorise inside the bracket. think of two numbers that MULTIPLY to -90 but also ADD to -1
the numbers were -10 and +9
3(r-10(r+9)

Answer 17

:D thanks

Answer 18

no probs and thanx for the medal