2
63x + b - 12 + 8
3. ?
Answers
Answer:
Denote the roots by a,2a,b; then we have
3a+b=
12
7
,2a
2
+3ab=−
8
21
,2a
2
b=−
8
15
.
From the first two equations, we obtain
8a
2
−2a−3=0
∴a=
4
3
or −
2
1
and b=−
3
5
or
12
25
.
It will be found on trial that the values a=−
2
1
,b=
12
25
do not satisfy the third equation 2a
2
b=−
8
15
;
hence we are restricted to the values
a=
4
3
,b=−
3
5
.
Thus the roots are
4
3
,
2
3
,−
3
5
.
Step-by-step explanation:
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Answer:
Step-by-step explanation:
Denote the roots by a,2a,b; then we have
3a+b=
12
7
,2a
2
+3ab=−
8
21
,2a
2
b=−
8
15
.
From the first two equations, we obtain
8a
2
−2a−3=0
∴a=
4
3
or −
2
1
and b=−
3
5
or
12
25
.
It will be found on trial that the values a=−
2
1
,b=
12
25
do not satisfy the third equation 2a
2
b=−
8
15
;
hence we are restricted to the values
a=
4
3
,b=−
3
5
.
Thus the roots are
4
3
,
2
3
,−
3
5
.