a) 12,78 : 0,4 + 51,92

= 31,95 + 51,92

= 83,87

b) 215,34 - 39,9 : 0,5

= 215,34 - 79,8

= 135,54

ai tick cho mik đc 250 điểm hỏi đáp với . nếu các bạn tick mik thì gửi tin nhắn mik tick lại

a) 100

b) 10

a) 45,75 + 25,5 x 3,5 - 35

= 45, 75 + 89,25 - 35

= 135 - 35

= 100

b) 166,32 : 46,2 + 16 x 0,4

= 3,6 + 6,4

= 10

a) 45,75 + 25,5 × 3,5 - 35 = 45,75 + 89,25 - 35 = 135 - 35 = 100

b) 166,32 : 46,2 + 16 × 0,4 = 3,6 + 6,4 = 10

a) \(12,78:0,4+51,92\)

\(=31,95+51,92\)

\(=83,87\)

b) \(215,34-38,9:0,5\)

\(=215,34-77,8\)

\(=137,54\)

c) \(\left(34,6+13,82\right).2,1\)

\(=48,42.2,1\)

\(=101,682\)

d) \(\left(58,34-21,7\right):5\)

\(=36,64:5\)

\(=7,328\)

\(A=3\left|1-2x\right|-5\)

Ta có: \(\left|1-2x\right|\ge0\forall x\)

\(\Rightarrow3.\left|1-2x\right|-5\ge-5\forall x\)

\(\Rightarrow A\ge-5\forall x\)

Dấu "=" xảy ra

\(\Leftrightarrow3.\left|1-2x\right|=0\Leftrightarrow1-2x=0\Leftrightarrow x=\dfrac{1}{2}\)

Với a = 6 thì A = 2874 + 178 x 6 = 2874 + 1068

\(A=2x^2+2\sqrt{2}x+3\\ =2\left(x^2+\sqrt{2}x+\dfrac{3}{2}\right)\\ =2.\left(x^2+2.\dfrac{1}{\sqrt{2}}x+\dfrac{1}{2}+1\right)\\ =2.\left(x^2+2.\dfrac{1}{\sqrt{2}}x+\dfrac{1}{2}\right)+2\\ =2.\left(x+\dfrac{1}{\sqrt{2}}\right)^2+2\)

Ta có \(2.\left(x+\dfrac{1}{\sqrt{2}}\right)^2\ge0\forall x\)

\(2.\left(x+\dfrac{1}{\sqrt{2}}\right)^2+2\ge2\forall x\)

Dấu bằng xảy ra khi : \(x+\dfrac{1}{\sqrt{2}}=0\\ \Rightarrow x=\dfrac{-\sqrt{2}}{2}\)

Vậy \(Min_A=2\) khi \(x=\dfrac{-\sqrt{2}}{2}\)

\(tanx=\dfrac{1}{2}\Leftrightarrow\dfrac{sinx}{cosx}=\dfrac{1}{2}\Leftrightarrow cosx=2sinx\)

\(1+tan^2x=\dfrac{1}{cos^2x}\) \(\Leftrightarrow cos^2x=\dfrac{4}{5}\)

=> \(sin2x=2sinx.cosx=cos^2x\)

\(A=\dfrac{2sin2x}{2-3cos2x}=\dfrac{2cos^2x}{2-3\left(cos^2x-1\right)}=\dfrac{8}{13}\)