Question

can you please help me with
x^2+x-20=0

Answer 1

(x+5)(x-4)

x=-5 & x=4

Answer 2

why is it a -5 & a +4?

Answer 3

cos when you factor "x^2+x-20=0" it will become (x+5)(x-4)=0

solve for x , take the first one... x+5=0 , x=-5 and solve for the second one.. x-4=0 , x=4

so x=4 &x=-5

and thats why! :)

Answer 4

ok, thank you

Answer 5

you're welcome :D

Answer 6

\[x^2+5x-4x-20=0\]
remember 5x-4x=1x=x so we the polynomial is still the same just written alittle different
now factor by grouping
first two terms have x in common: x^2+5x=x(x+5)
last two terms have -4 in common: -4(x+5)
so
\[x^2+5x-4x-20=x(x+5)-4(x+5)=0\]
x(x+5)-4(x+5)=0

we have two terms now one is x(x+5) and the other is -4(x+5)
both of these two terms have the factor (x+5) in common
so we can write
(x+5)(x-4)=0