Prove: (-a)(-b)=ab by using the axioms?

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Prove: (-a)(-b)=ab by using the axioms?

2007-06-11 19:59:30 · 3 answers · asked by bdx 1 in Science & Mathematics ➔ Mathematics

3 answers

(-a)(-b) =
(-1)(a)(-1)(b) =
(-1)(-1)(a)(b) =
(1)(a)(b) =
(a)(b) =
ab

2007-06-11 20:12:27 · answer #1 · answered by Helmut 7 · 0⤊ 0⤋

= (-1) x [ a x (-1) x b ]
= (-1) x [ (-1) x a x b ]
= (-1) x [ (-1) x ab ]
= (-1) x (-1) x (ab)
= [(-1) x (-1)] x ab
= 1 x ab
= ab

2007-06-11 22:10:10 · answer #2 · answered by Como 7 · 0⤊ 0⤋

-a = -a million X a for this reason, (-a million X a) X b = a X b X -a million = -1ab, then take -a million out to get -(ab) (-a million)b = -a million X b = -b (-a)(-b) = (-a million X a)(-a million X b) [improve] = a X b X -a million X -a million [-a million X -a million = a million] = a X b X a million = a X b = ab

2016-11-23 13:07:40 · answer #3 · answered by Anonymous · 0⤊ 0⤋