Question

tìm x :

a) (3x - 2⁴ ) . 7³ = 2 . 7⁴ 

b) 2130 - ( x = 130 ) +72 = (-64)

c) 15 - ( -x + 18 )= (-24)

d) 10 - |x+ 3 | = (-4) - (-10)

 

Answer 1

a.

\(\left(3x-2^4\right)\times7^3=2\times7^4\)

\(3x-2^4=2\times7^4\div7^3\)

\(3x-16=2\times7\)

\(3x-16=14\)

\(3x=14+16\)

\(3x=30\)

\(x=\frac{30}{3}\)

\(x=10\)

b.

\(2130-\left(x+130\right)+72=-64\)

\(2130-\left(x+130\right)=-64-72\)

\(2130-\left(x+130\right)=-136\)

\(x+130=2130+136\)

\(x+130=2266\)

\(x=2266-130\)

\(x=2136\)

c.

\(15-\left(-x+18\right)=-24\)

\(\left(-x+18\right)=15+24\)

\(-x+18=39\)

\(-x=39-18\)

\(-x=21\)

\(x=-21\)

d.

\(10-\left|x+3\right|=-4-\left(-10\right)\)

\(\left|x+3\right|=10+4-10\)

\(\left|x+3\right|=4\)

\(x+3=\pm4\)

TH1:

\(x+3=4\)

\(x=4-3\)

\(x=1\)

TH2:

\(x+3=-4\)

\(x=-4-3\)

\(x=-7\)

Vậy x = 1 hoặc x = - 7.

Answer 2

bạn ơi câu b sao lại là 

(x=130)