b= 8,16 chia 1.32 +3.48 -0.346chia 2
8,16 : (1.32 + 3.48) - 0.345 : 2 =?
8,16 chia mo ngoac 1,32 + 3,48 dong ngoac -0,345 chia 2
Bài 1.32 trang 24 Toán 8 Tập 1: Thực hiên phép chia (7y5z2 – 14y4z3 + 2,1y3z4) : (−7y3z2).
`#3107`
\((7y^5z^2 – 14y^4z^3 + 2,1y^3z^4) \div (−7y^3z^2)\)
`= 7y^5z^2 \div (-7y^3z^2) - 14y^4z^3 \div (-7y^3z^2) + 2,1y^3z^4 \div (-7y^3z^2)`
`= -y^2 + 2yz - 0,3z^2`
8,16 chia 5,8
8,16 : 5,8 = 1,4068965517
Chúc bạn học tốt nhé !
10:1.32
Bài 1: Tính nhanh
a, A = 1.4+ 2.5 + 3.6+ …+ 66.69
b, B = 1.50 + 2.49 + 3.48 + …+ 49. 2+ 50. 1
giúp mình nha, cảm ơn mọi người rất nhiều ạ. ai đúng mình se tich nhé
a/
\(A=1.2+1.2+2.3+2.2+3.4+3.2+...+66.67+66.2=\)
\(=\left(1.2+2.3+3.4+...+66.67\right)+2\left(1+2+3+...+66\right)\)
Đặt
\(B=1+2+3+...+66=\dfrac{66\left(1+66\right)}{2}=2211\)
Đặt
\(C=1.2+2.3+3.4+...+66.67\)
\(3C=1.2.3+2.3.3+3.4.3+...+66.67.3=\)
\(=1.2.3+2.3.\left(4-1\right)+3.4.\left(5-2\right)+...+66.67.\left(68-65\right)=\)
\(=1.2.3-1.2.3+2.3.4-2.3.4+3.4.5-...-65.66.67+66.67.68=\)
\(=66.67.68\Rightarrow C=\dfrac{66.67.68}{3}=22.67.68\)
\(\Rightarrow A=C+2B\) Bạn tự tính nhé
b/
\(B=2\left(1.50+2.49+3.48+...+25.26\right)=\)
Ta có
\(C=1.50+2.49+3.48+...+25.26=\)
\(\left(50-49\right).50+\left(50-48\right).49+\left(50-47\right).48+...+\left(50-25\right).26=\)
\(=50.50-49.50+50.49-48.49+50.48-47.48+50.26-25.26=\)
\(=50.\left(26+27+28+...+50\right)-\left(25.26+26.27+27.28+...+49.50\right)\)
Ta có
\(D=26+27+28+...+50=\dfrac{25.\left(26+50\right)}{2}=950\)
Ta có
\(E=25.26+26.27+27.28+...+49.50\)
\(3E=25.26.3+26.27.3+27.28.3+...+49.50.3=\)
\(=25.26.\left(27-24\right)+26.27.\left(28-25\right)+...+49.50.\left(51-48\right)=\)
\(=-24.25.26+25.26.27-25.26.27+26.27.28-...-48.49.50+49.50.51=\)
\(=49.50.51-24.25.26\)
\(\Rightarrow E=\dfrac{49.50.51-24.25.26}{3}\)
\(\Rightarrow C=50D-E\)
\(B=2C\)
Bạn tự tính nhé
tinh hop li
a)1.50+2.49+3.48+........+49.2+50.1
b)1-3+3^2-3^3+....+3^98-3^99
c)1.3+2.4+3.5+....+99.101+100.102
a) (131,4 - 80,8 ) :2,3 + 21,84 x 2
b) 8,16 : ( 1,32 + 3,48) - 0,345 : 2
1.50+2.49+3.48+...+48.3+49.2+50.1