Question

Tìm x , biết

a, \(3^2\left(x+14\right)-5^2=5.4\)

b, \(720:\left[41-\left(2x-5\right)\right]=2^3.5\)

Ai nhanh minh tick

Answer 1

a, \(3^2\left(x+14\right)-5^2=5.4\)

\(\Rightarrow9\left(x+14\right)-25=20\)

\(\Rightarrow9x+126=20+25\)

\(\Rightarrow9x+126=45\)

\(\Rightarrow9x=45-126\)

\(\Rightarrow9x=-81\Rightarrow x=-9\)

Vậy x = 9 

Answer 2

a,\(3^2\left(x+14\right)-5^2=5.4\)

\(\Rightarrow9\left(x-14\right)-25=20\)

\(\Rightarrow9\left(x-14\right)=20+25=45\)

\(\Rightarrow x-14=45:9=5\)

\(\Rightarrow x=5+14\)

\(\Rightarrow x=19\)

Vậy x = 19

b,\(720:\left[41-\left(2x-5\right)\right]=2^3.5\)

\(720:\left[41-2x+5\right]=40\)

\(\Rightarrow41+5-2x=720:40\)

\(\Rightarrow46-2x=18\)

\(\Rightarrow2x=46-18=28\)

\(\Rightarrow x=28:2\)

\(\Rightarrow x=14\)

Vậy x = 14

~Study well~

Answer 3

b, \(720\div\left[41-\left(2x-5\right)\right]=2^3.5\)

\(\Rightarrow720\div\left[41-\left(2x-5\right)\right]=8.5\)

\(\Rightarrow720\div\left[41-\left(2x-5\right)\right]=40\)

\(\Rightarrow41-\left(2x-5\right)=\frac{720}{40}\)

\(\Rightarrow41-\left(2x-5\right)=18\)

\(\Rightarrow2x-5=41-18\)

\(\Rightarrow2x-5=23\)

\(\Rightarrow2x=23+5\)

\(\Rightarrow2x=28\Rightarrow x=\frac{28}{2}=14\)

Vậy x = 14 

Answer 4

Bạn làm sai rồi

x+14 chứ đâu phải x - 14 đâu

Answer 5

\(3^2\left(x+14\right)-5^2=5.4\)

\(9\left(x+14\right)-25=20\)

\(9\left(x+14\right)=20+25\)

\(9\left(x+14\right)=45\)

\(x+14=45:9\)

\(x+14=5\)

\(x=5-14\)

\(x=-9\)

~ Hok tốt ~

Answer 6

a, 3²(x+14)-5²=5.4

=> 9(x+14)-25=20

=> 9(x+14)=45

=> x+14=5

=>x=-9

Answer 7

720:[41-(2x-5)]=2³.5

=>720:[41-(2x-5)]=40

=>41-(2x-5)=18

=>46-2x=18

=>2x=28

=>x=14