B² - 4ac
= 8² - 4*(-2)*(-9)
= 64 - 72
= -8
Answer:
81
Step-by-step explanation:
27 total of pupils.
girls 1×27=27
boys 2×27=54
total 54+27=81
<h2><em>y
2
+
6
y
−
16
=
(
y
+
8
)
(
y
−
2
)
</em></h2><h2 /><h2><em>Explanation:
</em></h2><h2><em>Note that in general:
</em></h2><h2 /><h2><em>(
y
+
a
)
(y
−
b
)
=
y
2
+
(
a
−
b
)
y
−
a
b
</em></h2><h2 /><h2><em>So we want to find a pair of factors a and b of 16 which differ by 6
. </em></h2><h2><em>The pair 8
,
2 works in that 8−
2
=
6 and 8
⋅
2=
16
.
</em></h2><h2 /><h2><em>Hence:
</em></h2><h2><em>
y
2
+
6
y
−
16
=
(
y+
8
)
(
y
−
2
)</em></h2><h2><em>y=2,-8</em></h2>
I think it might be 40 I’m not sure but good luck
2:5
4:10
66:165
Is that correct?
