a) (3x-24).7³ = 2.$$7^{4}$$
⇔ (3x-24).343 = 4082
⇔ 3x-24 =14
⇔ 3x = 38
⇔ x= $$\frac{38}{3}$$
b) 2².x + 3².x = 260
⇔ 4x + 9x = 260
⇔ 13x = 260
⇔ x = 20
c) 5².x - 3².x =320
⇔ 25x - 9x =320
⇔16x = 320
⇔ x=20
@minhle8
c)
Đáp án:
a)(3*x-24)*7^3=2 *7^4
(3*x-24)=2 *7^4 : 7^3
(3*x-24)=2*7
3*x-24=14
3*x=14+24
3*x=38
x=38:3
x=38/3
Vậy: x=38/3
_______________________
b)2^2 *x+3^2 *x=260
x*(2^2 +3^2)=260
x*13=260
x=260:13
x=20
Vậy: x=20
____________________
c)5^2 *x -3^2 *x=320
x*(5^2 -3^2)=320
x*16=320
x=320:16
