5^7.31-5^7.26=
Thu gọn:
\(\frac{50^{15}.13^{18}}{25^7.26^{15}.5^{16}}\)
\(\frac{50^{15}\cdot13^{18}}{25^7\cdot26^{15}\cdot5^{16}}=\frac{5^{15}\cdot2^{15}\cdot13^{18}}{5^{14}\cdot13^{15}\cdot2^{15}\cdot5^{16}}=\frac{5^{15}\cdot2^{15}\cdot13^{18}}{5^{30}\cdot2^{15}\cdot13^5}=\frac{13^{13}}{5^{15}}\)
bạn Đào Trọng Luân ơi, hình như sai thì phải!
tim a/b biet a=4/7.31+6/7.31+9/10.41+7/10.57/b=7/19.31+5/19.43+3/23.43+11/23.57
A=4/(7.31)+6/(7.41)+9/(10.41)+7/(10.51)
=20/(35.31)+30/(35.41)+45/(50.41)
+35/(50.51)
=5[4/(35.31)+6/(35.41)+9/(50.41)
+7/(50.51)]
=5(1/31-1/35+1/35-1/41+1/41-1/50
+1/50-1/57)
=5(1/31-1/57)
B=7/(19.31)+5/(19.43)+3/(23.43)
+11/(23.57)
tương tự ta nhân cả tử và mẫu của các phân số biểu thức B với 2
=>B=2(1/31-1/57)
=>A/B=5/2
\(\frac{60^8}{12^7.5^8}=\)
\(\frac{50^{15}.13^{18}}{25^7.26^{15}.5^{16}}=\)
\(10^4:5^3=\)
\(\frac{60^8}{12^7.5^8}=\frac{2^{16}.3^8.5^8}{2^{14}.3^7.5^8}=\frac{2^2.3}{1}=12\)
\(\frac{50^{15}.13^{18}}{25^7.26^{15}.5^{16}}=\frac{2^{15}.5^{30}.13^{18}}{5^{30}.2^{15}.13^{15}}=2197\)
\(\frac{10^4}{5^3}=\frac{5^4.2^4}{5^3}=80\)
\(\frac{60^8}{12^7.5^8}=\frac{2^3.3}{1}=12\)
\(\frac{50^{15}.13^{18}}{25^7.26^{15}}=2197\)
\(10^4:5^3=10000:125=80\)
Bài 5: Thực hiện phép tính \(\dfrac{4}{7.31}+\dfrac{6}{7.41}+\dfrac{9}{10.41}+\dfrac{7}{10.57}\)
=4/217+6/287+9/410+7/570
=130/1767
\(y=\frac{50^{15}.13^{18}}{25^7.26^{15}.5^{16}}\) Tính
\(y=\frac{50^{15}.13^{18}}{25^7.26^{15}.5^{16}}=\frac{\left(2.5\right)^{15}.13^{18}}{\left(5^2\right)^7.\left(2.13\right)^{15}.5^{16}}=\frac{2^{15}.5^{15}.13^{18}}{5^{14}.5^{16}.2^{15}.13^{15}}=\frac{2^{15}.5^{15}.13^{18}}{5^{30}.2^{15}.13^{15}}=\frac{13^3}{15^{15}}\)
7.26 - 2.5 * (a-1,4) với a= 2,8
7.26 - 2.5 * (a-1,4)
= 128 - 10*(2,8 - 1,4)
= 128 - 10*1.4
= 114
Thay a=2,8 vào biểu thức 7,26-2,5(a-1,4) ta được:
\(7,26-2,5\cdot1,4=3,76\)
A = 4/7.31 + 6/7.41 + 9/10.41 + 7/10.57 ; B = 7/19.31 + 5/19.43 + 3/23.43 + 11/23.57 Tính nhanh A/B
A=
7.31
4
+
7.41
6
+
10.41
9
+
10.57
7
⇒
5
A
=
35.31
4
+
35.41
6
+
50.41
9
+
50.57
7
\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{35}+\dfrac{1}{35}-\dfrac{1}{41}+\dfrac{1}{41}-\dfrac{1}{50}+\dfrac{1}{50}-\dfrac{1}{57}
5
A
=
31
1
−
35
1
+
35
1
−
41
1
+
41
1
−
50
1
+
50
1
−
57
1
\dfrac{A}{5}=\dfrac{1}{31}-\dfrac{1}{57}=\dfrac{26}{31.57}\Rightarrow A=\dfrac{130}{31.57}
5
A
=
31
1
−
57
1
=
31.57
26
⇒A=
31.57
130
1) cho A=4/7.31+6/7.41+9/10.41+7/10.57
B= 7/19.31+5/19.43+3/23.43+11/23.57
Tính A/B
\(\frac{A}{5}=\frac{4}{35.31}+\frac{6}{35.41}+\frac{9}{50.41}+\frac{7}{50.57}=\frac{35-31}{35.31}+\frac{41-35}{35.41}+\frac{50-41}{50.41}+\frac{57-50}{50.57}\)
\(\frac{A}{5}=\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> A = 5. \(\left(\frac{1}{31}-\frac{1}{57}\right)\)
\(\frac{B}{2}=\frac{7}{38.31}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}=\frac{38-31}{31.38}+\frac{43-38}{38.43}+\frac{46-43}{43.46}+\frac{57-46}{46.57}\)
\(\frac{B}{2}=\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}=\frac{1}{31}-\frac{1}{57}\)=> B = 2.\(\left(\frac{1}{31}-\frac{1}{57}\right)\)
A/B = 5/2
Tìm tỉ số A/B biết
A=4/7.31+6/7.41+9/10.41+7/10.57 và B=7/19.31+5/7.43+3/23.43+11/23.57