更新1:
Thank you everyone!! it really helped!!
(2√15 + √5) x (√15+ 3√5)?
2009-07-23 6:54 pm
please help me solve this rational no problem! its very urgent!! due tomorrow!!
回答 (4)
2009-07-23 7:05 pm
✔ 最佳答案
(2√15 + √5)(√15+ 3√5) Use "foil" pattern:2√15² + √5√15+ 6√5√15 + 3√5²
Note that √5√15 = √5√5√3 = 5√3
2•15 + 5√3 + 6•5√3 + 3•5
45 + 35√3
2009-07-23 7:04 pm
[2sqrt(15) + sqrt(5)][sqrt(15) + 3sqrt(5)]
Multiply using FOIL
First: 2sqrt(15)sqrt(15) = 2(15) = 30
Outer: 2sqrt(15)3sqrt(5) = 6sqrt(75) = 6(5)sqrt(3) = 30sqrt(3)
Inner: sqrt(5)sqrt(15) = sqrt(75) = 5sqrt(3)
Last: sqrt(5)3sqrt(5) = 3(5) = 15
Putting it all together: 30 + 30sqrt(3) + 5sqrt(3) + 15
= 45 + 35sqrt(3)
Multiply using FOIL
First: 2sqrt(15)sqrt(15) = 2(15) = 30
Outer: 2sqrt(15)3sqrt(5) = 6sqrt(75) = 6(5)sqrt(3) = 30sqrt(3)
Inner: sqrt(5)sqrt(15) = sqrt(75) = 5sqrt(3)
Last: sqrt(5)3sqrt(5) = 3(5) = 15
Putting it all together: 30 + 30sqrt(3) + 5sqrt(3) + 15
= 45 + 35sqrt(3)
2009-07-23 7:02 pm
(2â15 + â5)(â15 + 3â5)
= 2â(15 * 15) + (2 * 3)â(15 * 5) + â(5 * 15) + 3â(5 * 5)
= 2(15) + 6â(5^2 * 3) + â(5^2 * 3) + 3(5)
= 30 + 6(5)â3 + 5â3 + 15
= 30 + 30â3 + 5â3 + 15
= 30 + 35â3 + 15
= 2â(15 * 15) + (2 * 3)â(15 * 5) + â(5 * 15) + 3â(5 * 5)
= 2(15) + 6â(5^2 * 3) + â(5^2 * 3) + 3(5)
= 30 + 6(5)â3 + 5â3 + 15
= 30 + 30â3 + 5â3 + 15
= 30 + 35â3 + 15
2009-07-23 7:49 pm
( 2 ) ( 15 ) + 6 â75 + â75 + 15
45 + 7â75
45 + 35 â3
45 + 7â75
45 + 35 â3
收錄日期: 2021-05-01 12:39:29
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