Tính giá trị của biểu thức
A= 725:(Mx2,5-15)+288,7 khi M=10
B cho biểu thức B= 0,36x72+9x0,28x4xM
Tìm giá trị của M để B= 41,04
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a. Thay a = 14, b = 15, c = 10, ta có:
\(a=a\times b+200\)
\(=>a=14\times15+200\)
\(=>a=210+200=410\)
___
\(b=a\times b\times c\)
\(=>b=14\times15\times10=2100\)
b. Vì 410 < 2100 nên a < b.
\(#NqHahh\)
a: Khi a=14 và b=15 thì \(A=14\cdot15+200=210+200=410\)
Khi a=14 và b=15 và c=10 thì \(B=14\cdot15\cdot10=210\cdot10=2100\)
b: A=410
B=2100
=>A<B
B = 0,36 + 72 + 9 x 0,28 x 4 x m
9 x 0,25 x 4 x m = 41,04 - 0,36 - 72
= SAI ĐỀ NHA
~~ tk mk nha ~~
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a: Khi x=-2 thì \(M=3-\left(-2-1\right)^2=3-9=-6\)
Khi x=0 thì \(M=3-\left(0-1\right)^2=2\)
Khi x=3 thì \(M=3-\left(3-1\right)^2=3-2^2=-1\)
b: Để M=6 thì \(3-\left(x-1\right)^2=6\)
\(\Leftrightarrow\left(x-1\right)^2=-3\)(loại)
c: \(M=-\left(x-1\right)^2+3\le3\forall x\)
Dấu '=' xảy ra khi x=1
a, Thay x=-2 vào M ta có:
\(M=3-\left(-2-1\right)^2=3-\left(-3\right)^2=3-9=-6\)
Thay x=0 vào M ta có:
\(M=3-\left(0-1\right)^2=3-\left(-1\right)^2=3-1=2\)
Thay x=3 vào M ta có:
\(M=3-\left(3-1\right)^2=3-2^2=3-4=-1\)
b, Để M=6 thì:
\(3-\left(x-1\right)^2=6\\ \Leftrightarrow\left(x-1\right)^2=-3\left(vô.lí\right)\)
c, Ta có: \(\left(x-1\right)^2\ge0\forall x\)
Dấu "=" xảy ra \(\Leftrightarrow x=1\)
\(\Rightarrow M=3-\left(x-1\right)^2\le3\)
Dấu "=" xảy ra \(\Leftrightarrow x=1\)
Vậy \(M_{max}=3\Leftrightarrow x=1\)
Câu 5:
\(D\left(2\right)=21a+9b-6a-4b\)
\(D\left(2\right)=\left(21a-6a\right)+\left(9b-4b\right)\)
\(D\left(2\right)=15a+5b\)
Mà: \(3a+b=18\Rightarrow b=18-3b\)
\(\Rightarrow D\left(2\right)=15a+5\left(18-3b\right)\)
\(D\left(2\right)=15a+90-15a\)
\(D\left(2\right)=90\)
Vậy: ...
a) Thay a=36,35 ta có
M = 12,5 x ( 36,35 + 64,35 ) - 225
M = 12,5 x 100,7 - 225
M = 1258,75 - 225
M = 1033,75
b) Thay M = 755 ta có
755 = 12,5 x (a + 64,35) - 225
12,5 x (a + 64,35) = 755 - 225
12,5 x (a + 64,35) = 530
a + 64,35 = 530 : 12,5
a + 64,35 = 42,4
a = 42,4 - 64,35
a = -21,95
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