Question

x square - 18 x + 80 factorise​

Answer 1

I found:

x

1

=

−

8

x

2

=

−

10

Explanation:

Start by taking

80

to the right and get:

x

2

+

18

x

=

−

80

now you need a number that multiplied by

2

gives

18

...could be

9

!

So, add and subtract NOT

9

but

9

2

=

81

!

x

2

+

18

x

+

81

−

81

=

−

80

take

−

81

to the right:

x

2

+

18

x

+

81

=

81

−

80

so that you can write:

(

x

+

9

)

2

=

1

root square both sides:

x

+

9

=

±

√

1

=

±

1

So you get two solutions:

x

1

=

−

8

x

2

=

−

10

Answer 2

Answer:

Step-by-step explanation:

X2-18x+80

X2-8x-10x+80

X(x-8)-10(x-8)

(x-8)(x-10)

X-8=0

X=8

X-10=0

X=10