a, 27.26+27.64

=27.(26+64)

=27.90

=2430

b,25.37+25.63-150

=25.(37+63)-150

=25.110-150

=2750-150

=2600

c,425.7.4=170.60

=1700.7=170.10.6

=1700.7-1700.6

=1700.(7-6)

=1700

d,0.9.14+6.17.12+19.4.18

=0+6.17.12+19.4.18

=6.3.4.17+19.4.18

=18.4.17+19.4.18

=18.4.(17+19)

=72.36=2592

Ta có:

425*27+425*72+425=425*(27+72+1)=425*100=42500

425x27+425x72+425

=425x27+425x72+425x1

=425x(27+72+1)

=425x100

=42500

Ta có: `a_[max]=40(m//s^2)`

   Mà `A=8(cm)=0,08(m)`

 `=>\omega=\sqrt{[a_[max]]/A}=10\sqrt{5}(rad//s)`

    `=>f=[\omega]/[2\pi]=[5\sqrt{5}]/[\pi] (Hz)`

425 x 32 + 69 x 425 - 425

= 425 x 32 + 69 x 425 - 425 x 1

= 425 x (32+69-1)

= 425 x 100

=  42500

1) \(7.4^x=7.4^3\Leftrightarrow4^x=4^3;x=3\)

2) \(\frac{3}{2.5^x}=\frac{3}{2.5^{12}}\Leftrightarrow5^x=5^{12};x=12\)

\(2^x=2.2^8=2^9;x=9\)

4) \(5.3^x=7.3^5-2.3^5\Leftrightarrow5.3^x=3^5.\left(7-2\right)\)

\(\Leftrightarrow3^5.x=3^5.5;x=5\)

\(\Leftrightarrow x-12=7\cdot4=28\)

hay x=40

7.4:

a: ĐKXĐ: x>=0

\(\sqrt{4x}+3\cdot\sqrt{25x}-2\cdot\sqrt{49x}=\sqrt{16x}-4\)

=>\(2\sqrt{x}+3\cdot5\sqrt{x}-2\cdot7\sqrt{x}=4\sqrt{x}-4\)

=>\(2\sqrt{x}+15\sqrt{x}-14\sqrt{x}=4\sqrt{x}-4\)

=>\(-\sqrt{x}=-4\)

=>\(\sqrt{x}=4\)

=>x=16(nhận)

b: ĐKXĐ: x>=0

\(2\sqrt{8x}-\sqrt{18x}+\sqrt{50x}=1\)

=>\(2\cdot2\sqrt{2x}-3\sqrt{2x}+5\sqrt{2x}=1\)

=>\(4\sqrt{2x}-3\sqrt{2x}+5\sqrt{2x}=1\)

=>\(6\sqrt{2x}=1\)

=>\(\sqrt{2x}=\frac16\)

=>\(2x=\frac{1}{36}\)

=>\(x=\frac{1}{72}\) (nhận)

c: ĐKXĐ: x>=2

Ta có: \(\sqrt{4x-8}+\sqrt{9x-18}-\sqrt{16x-32}=3\)

=>\(2\sqrt{x-2}+3\sqrt{x-2}-4\sqrt{x-2}=3\)

=>\(\sqrt{x-2}=3\)

=>x-2=9

=>x=11(nhận)

d: ĐKXĐ: x>=1

\(\frac13\sqrt{x-1}+2\cdot\sqrt{4x-4}-12\cdot\sqrt{\frac{x-1}{25}}=\frac{29}{15}\)

=>\(\frac13\cdot\sqrt{x-1}+2\cdot2\sqrt{x-1}-12\cdot\frac{\sqrt{x-1}}{5}=\frac{29}{15}\)

=>\(\frac{13}{3}\sqrt{x-1}-\frac{12}{5}\sqrt{x-1}=\frac{29}{15}\)

=>\(\frac{29}{15}\cdot\sqrt{x-1}=\frac{29}{15}\)

=>\(\sqrt{x-1}=1\)

=>x-1=1

=>x=2(nhận)

e: ĐKXĐ: x>=3/2

\(3\sqrt{2x-3}+2\cdot\sqrt{8x-12}=\sqrt{18x-27}+9\)

=>\(3\sqrt{2x-3}+2\cdot2\sqrt{2x-3}=3\sqrt{2x-3}+9\)

=>\(4\sqrt{2x-3}=9\)

=>\(\sqrt{2x-3}=\frac94\)

=>\(2x-3=\frac{81}{16}\)

=>\(2x=\frac{81}{16}+3=\frac{81}{16}+\frac{48}{16}=\frac{129}{16}\)

=>\(x=\frac{129}{32}\) (nhận)

f: ĐKXĐ: 1<=x<=5

\(\sqrt{9x-9}+\sqrt{4x-4}-\sqrt{16x-16}=\sqrt{5-x}\)

=>\(3\sqrt{x-1}+2\sqrt{x-1}-4\sqrt{x-1}=\sqrt{5-x}\)

=>\(\sqrt{5-x}=\sqrt{x-1}\)

=>5-x=x-1

=>2x=6

=>x=3(nhận)

g: ĐKXĐ: x>=5

\(\sqrt{x+2}+\sqrt{4x+8}-\sqrt{9x+18}=\sqrt{x-5}\)

=>\(\sqrt{x+2}+2\cdot\sqrt{x+2}-3\cdot\sqrt{x+2}=\sqrt{x-5}\)

=>\(\sqrt{x-5}=0\)

=>x-5=0

=>x=5(nhận)

= 48.(9.8+7.4)+52.(72+2.14)

=48.100+52.100

=100(48+52)

=100.100

=10000

đáp án =10000

`3/7 .4/11+3/7 .7/11-2`

`= 3/7 . ( 4/11 + 7/11)-2`

`= 3/7 . 11/11 -2`

`=3/7 . 1-2`

`= 3/7-2`

`= 3/7 - 14/7`

`=-11/7`

`3/7*4/11+3/7*7/11-2`

`=3/7*(4/11+7/11)-2`

`=3/7*1-2`

`=3/7-2`

`=3/7-14/7`

`=-11/7`