Express (2-3√5)^2 in the form a+b√5, where a and b are intergers.
Can you show me how to work it out so I can understand it.
2007-11-23 07:58:39 · 5 answers · asked by Luke M 1 in Science & Mathematics ➔ Mathematics
(2-3√5)^2
(2-3√5)(2-3√5)
4-6√5-6√5+(9 x 5)
4-6√5-6√5+45
49-12√5
2007-11-23 19:57:57 · answer #1 · answered by Anonymous · 0⤊ 0⤋
(2-3â5)^2
=(2-3â5)(2-3â5)
= 4 - 6â5 - 6â5 + 9*5
= 4 - 12â5 + 45
= ans
2007-11-23 16:05:38 · answer #2 · answered by harry m 6 · 0⤊ 1⤋
(2-3â5)^2
= 4+45 - 12â5 = 49-12â5
since (a+b)^2 = a^2 +b^2 + 2ab
(Keep it simple)
2007-11-23 16:25:48 · answer #3 · answered by Anonymous · 0⤊ 0⤋
4 -12sqrt 5 + 45=49 -12sqrt 5
use the FOIL method to multiply (2-3sqrt5)(2-3sqrt5)
2007-11-23 16:09:31 · answer #4 · answered by mom 7 · 0⤊ 1⤋
(2 - 3 SQRT(5))^2 = (2 - 3 SQRT(5)) (2 - 3 SQRT(5))
Use F.O.I.L. method.
2 x 2 + 2 x -3 SQRT(5) + -3 SQRT(5) x 2 + -3SQRT(5) x -3SQRT(5)
4 - 12 SQRT(5) + 45 = 49 - 12 SQRT(5)
2007-11-23 16:06:24 · answer #5 · answered by lhvinny 7 · 0⤊ 1⤋