x square - 18 x + 80 factorise
Answers
Answered by
2
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
Answered by
1
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
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