Question

1) Thực hiện phép tính
a) 78 - 12.5 + 3²
b) 4² . 55 + 2 . 45 . 8 - 2024⁰
c) 1800 : {49 - [ 2.(6² -34)³ - 5⁴ : 5³]}
d)\(\dfrac{15.2^{11}.3^{10}-6^{11}}{12.6^{10}+7.4^6.9^6}\)

2) Tìm x biết

27 : 3^x + 31 = 2.5² - 4^{2
Giải gấp cho em với ạ}
 

Answer 1

2:

=>27:3^x=2*25-16-31=50-47=3

=>3^x=27/3=9

=>3^x=3^2

=>x=2

1:

b: \(=16\cdot55+16\cdot45-1\)

=16(55+45)-1

=1600-1

=1599

c: \(=\dfrac{1800}{49-\left[2\cdot\left(36-34\right)^3-5\right]}\)

\(=\dfrac{1800}{49-2\cdot2^3+5}=\dfrac{1800}{49-16+5}=\dfrac{1800}{38}\)=900/19

d: \(=\dfrac{5\cdot3^{11}\cdot2^{11}-3^{11}\cdot2^{11}}{2^{10}\cdot3^{10}\cdot2^2\cdot3+7\cdot2^{12}\cdot3^{12}}\)

\(=\dfrac{3^{11}\cdot2^{11}\left(5-1\right)}{2^{12}\cdot3^{11}\left(1+7\cdot3\right)}=\dfrac{1}{2}\cdot\dfrac{4}{1+21}=\dfrac{4}{22\cdot2}=\dfrac{1}{11}\)