Please explain how -2(b+4)(b+5) equals (b+5-2)?
回答 (6)
2009-06-02 8:37 am
✔ 最佳答案
If -2(b+4)(b+5)=(b+5-2) then -2(b^2+5b+4b+20)=b+3then -2(b^2+9b+20)=b+3 or,-2b^2-18b-40=b+3 then -2b^2-19b-43=0
then 2b^2+19b+43=0.Now you solve for b. [ANSWER]
2009-06-02 7:15 pm
-2(b + 4)(b + 5)
= -2(b*b + 4*b + b*5 + 4*5)
= -2(b^2 + 4b + 5b + 20)
= -2*b^2 - 2*9b - 2*20
= -2b^2 - 18b - 40
â´ -2(b + 4)(b + 5) â b + 5 - 2
= -2(b*b + 4*b + b*5 + 4*5)
= -2(b^2 + 4b + 5b + 20)
= -2*b^2 - 2*9b - 2*20
= -2b^2 - 18b - 40
â´ -2(b + 4)(b + 5) â b + 5 - 2
2009-06-02 3:44 pm
If -2b^2-18b-40=b+3
then,-2b^2-19b-43=0
b=[19 + & - (361-344)^1/2]/-2=-11.56 & -7.438
then,-2b^2-19b-43=0
b=[19 + & - (361-344)^1/2]/-2=-11.56 & -7.438
2009-06-02 3:43 pm
-2(b+4)(b+5)
this solution is possible by mistake or refer to higher order derivatives and use L-Hospital Rule
this solution is possible by mistake or refer to higher order derivatives and use L-Hospital Rule
2009-06-02 3:37 pm
how it can be equal?
if you expand the first equation, yield -2b^2 - 18b -40
if you expand the first equation, yield -2b^2 - 18b -40
2009-06-02 3:36 pm
Sorry to say, but it doesn't.
-2(b+4)(b+5) expands to:
-2b^2 - 16b - 30
sorry!
-2(b+4)(b+5) expands to:
-2b^2 - 16b - 30
sorry!
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