The sum of three numbers is 85. The second is 7 more than the first. The third is 2 more than four times the second. Find the nu
2 answers:
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Oooh, looks fun
ok
erm
we might want to know some properties
if
where a=a, then assume m=n
so
minus 17*2^x both sides
use u subsitution, u=2ˣ
solve
or
ac method
2 times 8=16
what 2 number multiply to get -17 and add to get 16
-16 and -1
2u²-1u-16u+8=0
(2u²-1u)+(-16u+8)=0
u(2u-1)+(-8)(2u-1)=0
(u-8)(2u-1)+0
u-8=0
u=8
2u-1=0
2u=1
u=1/2
now
u=2ˣ
8=2ˣ
3=x
and
-1=x
x=-1 and 3
neat problem
ok
erm
we might want to know some properties
if
so
minus 17*2^x both sides
use u subsitution, u=2ˣ
solve
or
ac method
2 times 8=16
what 2 number multiply to get -17 and add to get 16
-16 and -1
2u²-1u-16u+8=0
(2u²-1u)+(-16u+8)=0
u(2u-1)+(-8)(2u-1)=0
(u-8)(2u-1)+0
u-8=0
u=8
2u-1=0
2u=1
u=1/2
now
u=2ˣ
8=2ˣ
3=x
and
-1=x
x=-1 and 3
neat problem
