194x6x5-10x60x3-68x15

=30x194-30x60-2x34x15

=30x194-30x60-30x34

30x(194-60-34)

=30x100

=3000

194 x 6  x 5 - 10 x 60 x 3 - 68 x 15

= 194 x 30 - 30 x 60 - 34 x 2 x15 

= 194 x 30 - 30 x 60 - 34 x 30

= 30 x ( 194 - 60 - 34 )

= 30 x 100 = 3000

194 x 6 x 5 - 10 x 60 x 3 - 68 x 15

= 194 x 30 - 60 x 30 - 34 x 2 x 15

= 194 x 30 - 60 x 30 - 34 x 30

= ( 194 - 60 - 34 ) x 30

= 100 x 30

= 3000

C1:

a. 786 x ( 32 +68)

= 786 x  100

= 78600

b. 2904 x 15 + 2904 x 35

= 43560 + 101640

= 145200

c.436 x 72 - 436 x 42

= 31392 - 18312

= 13080

d.194 x (87-7)

= 194 x 80

=15520

e.3332 : (4x49)

= 3332 : 196

= 17

f. 72 : 9 : 8

= (72 : 9) :8

= 1

g. (15 x 24) : 6

= 360 :6

= 60

m. 25 x(36 :9)

= 25 x 4

= 100

Cách 2:

a.786 x 32 + 786 x 68

= 25152 + 53448

= 78600

b. 2904 x ( 15 + 35)

= 2904 x 50

= 145200

c.436 x (72 -42)

= 436 x 30

= 13080

d.194 x 87 - 194 x7

= 16878 - 1358

= 15520

e. 3332 : (4 x 49)

= 3332 : 4 : 49

= 833 : 49 = 17

f. 72 : 9 :8

= 72 : (9 x8)

= 72 : 72

=1

g. (15 x 24) :6 

= 15 x (24 :6)

= 15 x 4

= 60

m. 25 x (36 :9)

= ( 25 x36 ):9

= 900 : 9

=100

câu hỏi gì có lun cả đáp án vậy

Sửa đề: \(98+99+\dfrac{142}{144}\) \(\rightarrow\dfrac{98}{99}+\dfrac{143}{144}\)  

Giải:

\(A=\dfrac{2}{3}+\dfrac{14}{15}+\dfrac{34}{35}+\dfrac{62}{63}+\dfrac{98}{99}+\dfrac{143}{144}+\dfrac{194}{195}\) 

\(A=\left(1-\dfrac{1}{3}\right)+\left(1-\dfrac{1}{15}\right)+\left(1-\dfrac{1}{35}\right)+...+\left(1-\dfrac{1}{195}\right)\) 

\(A=7-\left(\dfrac{1}{3}+\dfrac{1}{15}+\dfrac{1}{35}+...+\dfrac{1}{195}\right)\) 

\(A=7-\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{13.15}\right)\) 

\(A=7-\left[\dfrac{1}{2}.\left(\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+...+\dfrac{2}{13.15}\right)\right]\) 

\(A=7-\left[\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{13}-\dfrac{1}{15}\right)\right]\) 

\(A=7-\left[\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{15}\right)\right]\) 

\(A=7-\left[\dfrac{1}{2}.\dfrac{14}{15}\right]\) 

\(A=7-\dfrac{7}{15}\) 

\(A=\dfrac{98}{15}\) 

Chúc bạn học tốt!

\(x\cdot194-x\cdot93-x\cdot1=1200\) 

\(x\left(194-3-1\right)=1200\) 

\(100x=1200\) 

\(x=12\)

    x * 194 - x* 94 - x = 1200

     x* 194 - x*93 - x *1 = 1200

   x* ( 194 - 93 -1 ) = 1200

x * 100 = 1200 

x= 1200 : 100 

x= 12

\(\Leftrightarrow194x-93x-x=1200\)

\(\Leftrightarrow\left(194-93-1\right)x=1200\)

\(\Leftrightarrow100x=1200\)

\(\Leftrightarrow x=12.\)

119 + X = 194

119+x=194

x= 194-119=75

X=194-119

X=75

\(\dfrac{1293}{19}\times\dfrac{194}{2}=\dfrac{1293\times194}{19\times2}=\dfrac{250842}{38}\)

\(\dfrac{125421}{19}\)

ĐKXĐ: \(\left\{{}\begin{matrix}x-7>=0\\9-x>=0\end{matrix}\right.\)

=>7<=x<=9

\(\sqrt{x-7}+\sqrt{9-x}=3x^2-48x+194\)

=>\(\sqrt{x-7}-1+\sqrt{9-x}-1=3x^2-48x+192\)

=>\(\dfrac{x-7-1}{\sqrt{x-7}+1}+\dfrac{9-x-1}{\sqrt{9-x}+1}=3\left(x^2-16x+64\right)\)

=>\(\dfrac{x-8}{\sqrt{x-7}+1}-\dfrac{x-8}{\sqrt{9-x}+1}-3\left(x-8\right)^2=0\)

=>\(\left(x-8\right)\left(\dfrac{1}{\sqrt{x-7}+1}-\dfrac{1}{\sqrt{9-x}+1}-3x+24\right)=0\)

=>x-8=0

=>x=8(nhận)

A

A

A