1. thực hiện phép tính

a. 75-(3. 5² - 4. 2³)

= 75-(3. 25 - 4. 8)

= 75 - (75- 32)

= 75 - 43

= 32.

b. 18: 3² +5.2³ -27

= 18 : 9 + 5. 8 -27

= 2 + 40 - 27

= 42 - 27

= 15.

c. -12+34 = +(34 - 12) = 22.

d. 50.25+50.75-200

= 50. (25 + 75) - 200

= 50. 100 - 200

= 5000 - 200

= 4800.

e. -35+34+(-25)+16

= [-35 + (-25) ] + (16 + 34 )

= -60 + (16 + 34 )

= -60 + 50

= -10.

f. 27.75+28.75-270

= (27+28) . 75 - 270

= 55. 75 - 270

= 4125 - 270

= 3855.

g. 18.36+18.64-12.55-12.45

= 18 . (36+64) - 12. (55-45)

= 18 . 100 - 12. 10

= 1800 - 120

= 1680.

= 12 . (55+45)

= 12.100

=1200

12.55 + 12.45

= 12.(45+55)

= 12.100

= 1200

12 . 55 + 12 . 45

= 12 . ( 55 + 45 )

= 12 . 100

= 1200

a: \(-15-\left(-13+30\right)\)

\(=-15+13-30\)

\(=\left(-15-30\right)+13\)

=-45+13

=-32

b: \(225-150:\left(30+3^2\cdot5\right)\)

\(=225-150:\left(30+9\cdot5\right)\)

\(=225-150:75\)

=225-2

=223

c: \(18\cdot64+18\cdot36-1200\)

\(=18\left(64+36\right)-1200\)

\(=18\cdot100-12\cdot100\)

\(=6\cdot100=600\)

d: \(80-\left[130-\left(12-4\right)^2\right]\)

\(=80-130+\left(12-4\right)^2\)

\(=-50+8^2=64-50=14\)

\(\Leftrightarrow5^{2x-3}-2.25=25.3\\ \Leftrightarrow5^{2x-3}-50=75\\ \Leftrightarrow5^{2x-3}=125\\ \Leftrightarrow2x-3=3\\ \Leftrightarrow x=3\)

Mìk xin lỗi nha, câu a sai rùi, làm lại cho:

a) \(12.3^2-2^3.\left(2015^0+1^3\right)=12.9-8.\left(1+1\right)\)

\(=12.9-8.2=108-16=92\)

OK rùi đấy, tick nha thank you trước

x=3

\(\Rightarrow5^{2x-3}=5^2\cdot3+5^2\cdot2=5^2\cdot5=5^3\\ \Rightarrow2x-3=3\\ \Rightarrow x=3\)

5^2x-3-10=75

5^2x-3=85

\(5^{2x-3}-2.5^2=5^2.3\)

\(\Rightarrow5^{2x-3}-50=75\)

\(\Rightarrow5^{2x-3}=125=5^3\)

\(\Rightarrow2x-3=3\Rightarrow2x=6\Rightarrow x=3\)

5²ˣ⁻³ - 2.5² = 5².3

5²ˣ⁻³ - 2.25 = 25.3

5²ˣ⁻³ - 50 = 75

5²ˣ⁻³ = 75 + 50

5²ˣ⁻³ = 125

5²ˣ⁻³ =5³

2x - 3 = 3

2x = 3 + 3

2x = 6

x = 6 : 2

x = 3

\(5^{2x-3}-2.5^2=5^2.3\)

\(\Leftrightarrow5^{2x}:5^3-50=75\)

\(\Leftrightarrow5^{2x}:5^3=75+50\)

\(\Leftrightarrow5^{2x}:5^3=125\)

\(\Leftrightarrow5^{2x}=125.5^3\)

\(\Leftrightarrow5^{2x}=5^3.5^3\)

\(\Leftrightarrow5^{2x}=5^6\)

\(\Leftrightarrow2x=6\)

\(\Leftrightarrow x=6:2\)

\(\Leftrightarrow x=3\)

Vậy x=3