The difference of squares method:
a² - b² = (a-b ) (a+b)
54² - 46² = (54+46) · ( 54 + 46 )= 100 · 8 = 800
Answer: B)
Step-by-step explanation:
see the answer in the pic
x
=
−
7
or
x
=
−
8
Explanation:
Find a pair of factors of
56
with sum
15
.
The pair
7
,
8
works in that
7
⋅
8
=
56
and
7
+
8
=
15
Hence:
0
=
x
2
+
15
x
+
56
=
(
x
+
7
)
(
x
+
8
)
So:
x
=
−
7
or
x
=
−
8
Alternative method