\(B=13,3+\left(-13,3\right)+7,9\\ =\left[13,3+\left(-13,3\right)\right]+7,9\\ =0+7,9\\ =7,9\)
B = \(13.3+\left(-13.3\right)+7.9\)
B = \(0+7.9\)
B = \(7.9\)
Ta có:
B = 13,3 + (-13,3) + 7,9
= 13,3 - 13,3 + 7,9
= 7,9
\(B=13,3+\left(-13,3\right)+7,9\\ =\left[13,3+\left(-13,3\right)\right]+7,9\\ =0+7,9\\ =7,9\)
B = \(13.3+\left(-13.3\right)+7.9\)
B = \(0+7.9\)
B = \(7.9\)
Ta có:
B = 13,3 + (-13,3) + 7,9
= 13,3 - 13,3 + 7,9
= 7,9
5,7*6,2+1,9*4,5+5,7*13,3
a) -9/11 + 1/9 .18/3
b) 16/29 + -13/29 + 4/13 - 16/39
c) 9/24 . 14/25 + 5/24 . 11/25 - 1 và 9/24
d) (-111,82) + 13,3 - 8,18 + 16,7
Tính bằng cách hợp lí:
a) (−4,5) + 3,6 + 4,5 + (−3,6);
b) 2,1 + 4,2 + (−7,9) + (−2,1) + 7,9;
c) (−3,6) . 5,4 + 5,4 . (−6,4).
Chứng minh đẳng thức
a) \(\left(x-y\right)-\left(x-z\right)=\left(z+x\right)-\left(y+x\right)\)
b) \(\left(x-y+z\right)-\left(y+z-x\right)-\left(x-y\right)=\left(z-y\right)-\left(z-x\right)\)
c) \(a\left(b+c\right)-b\left(a-c\right)=\left(a+b\right)c\)
d) \(a\left(b-c\right)-a\left(b+d\right)=-a\left(c+d\right)\)
e) \(\left(a+b\right)\left(c+d\right)-\left(a+d\right)\left(b+c\right)=\left(a-c\right)\left(d-b\right)\)
f) \(\left(a-c\right)\left(b+d\right)-\left(a-d\right)\left(b+c\right)=\left(a+b\right)\left(d-c\right)\)
Chứng minh đẳng thức:
a) \(\left(a+b\right)\left(c+d\right)-\left(a+d\right)\left(b+c\right)=\left(a-c\right)\left(d-b\right)\)
b) \(\left(a-c\right)\left(b+d\right)-\left(a-d\right)\left(b+c\right)=\left(a+b\right)\left(d-c\right)\)
CMR
\(a,\left(a-b\right)+\left(c-d\right)=\left(a+c\right)-\left(b+d\right)\)
\(b,\left(a-b\right)-\left(c-d\right)=\left(a+d\right)-\left(b+c\right)\)
Hãy so sánh\(\left(\frac{a}{\left|b\right|}+\frac{\left|a\right|}{b}\right)\left(\frac{\left|a\right|}{b}+\frac{a}{\left|b\right|}\right)\)và \(\left(\frac{\left|a\right|}{\left|b\right|}+\frac{a}{b}\right)^2\), biết rằng a và b là hai số nguyên âm .
Rút gọn các biểu thức sau :
a) \(A=\left(a-b\right)+\left(a+b-c\right)-\left(a-b-c\right)\)
b) \(B=\left(a-b\right)-\left(b-c\right)+\left(c-a\right)-\left(a-b-c\right)\)
c) \(C=\left(-a+b+c\right)-\left(a-b+c\right)-\left(-a+b-c\right)\)
Chứng minh đẳng thức
\(\left(a-c\right)\left(b+d\right)-\left(a-d\right)\left(b+c\right)=\left(a+b\right)\left(d-c\right)\)