a) Tính tổng của ab + ba ( biết a + b = 6 )
b) Tinh hieu cua ab - ba ( biet a - b = 5 )
K
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CG
2
15 tháng 1 2017
a) Cho a=4,b=5
Ta có:\(4.5+5.4=20+20=40\)
b)Cho a=9, b=4
Ta có: \(9.4-4.9=36-36=0\)
KL
24 tháng 8 2017
A = 2004.2005
= (2000 + 4).2005
= 2000.2005 + 4.2005
B = 2000.2009
= 2000.(2005 + 4)
= 2000.2005 + 2000.4
=> A > B
@Nguyễn Hoàng Nina
19 tháng 11 2017
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5 tháng 12 2017
a) ta có AC + CB = 8+5 = 13 cm = AB. Vậy A, B , C thẳng hàng ; C nằm giữa A và B
b) không có tổng của 2 đoạn nào bằng đoạn còn lại nên 3 điểm không thẳng hàng. Nghĩa là nối 3 điểm với nhau từng đôi một ta được 1 tam giác đó.
a) ab + ba = a x 10 +b +b x 10 + a
=a x 10 + bx 10 + (b + a)
=(a + b) x 10 +6
=6 x 10 +6=6 x (10+1)
=6 x11= 66
b) ab - ba =(a x10 +b) - (b x10 +a)
=a x 10 - b x 10 - ( a-b)
=(a-b) x 10 - 5
= 5 x 10 -5
=50 -5
k cho mình nha
Giải:
a) theo bài ra ta có:
ab+ba
=aa+bb
Vì a+b=6 nên:
aa a+b =6 viết 6
+ bb a+b=6 viết 6
----------
66 vậy ta được kết quả là 66
b) theo bài ra ta có :
ab-ba
= aa-bb
Vì a-b=5 nên :
aa a-b=5 viết 5
- bb a-b=5 viết 5
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55 vậy ta có kết quả là 55