Question

tìm x

a)(x-6)² . (x-6) =64

b)(x+5)³ : (x+5) =144

c)3^x+4²=19⁶ : (19⁴ . 19)-2.1²⁰³⁶

d)(19x + 2.5²) : =5² - 4²

tính hợp lí(nếu  có thể)

(5²⁰⁰⁴ - 5²⁰⁰⁶):(5²⁰⁰⁵.5)

Answer 1

a)(x-6)² . (x-6) =64

(x-6)³=64

(x-6)³=4³

=>x-6=3

x=9

b)(x+5)³ : (x+5) =144

(x+5)²=144

(x+5)²=12²

=>x+5\(\in\left\{12;-12\right\}\)

\(\Rightarrow x\in\left\{7;-17\right\}\)

c)3^x+4²=19⁶ : (19⁴ . 19)-2.1²⁰³⁶

3^x+4²=19⁶ :19⁵-2

3^x+4²=19-2

3^x+4²=17

3^x+16=17

3^x=1

=>x=0

d)(19x + 2.5²) =5² - 4²

(19x + 2.5²) =25-16

(19x + 2.5²) =9

19x + 50 =9

19x = -41

x=\(\frac{-41}{19}\)

 

tính hợp lí(nếu  có thể)

(5²⁰⁰⁴ - 5²⁰⁰⁶):(5²⁰⁰⁵.5)

=(5²⁰⁰⁴ - 5²⁰⁰⁶):5²⁰⁰⁶

=(5²⁰⁰⁴ - 5²⁰⁰⁶).\(\frac{1}{5^{2006}}\)

=\(\frac{5^{2004}}{5^{2006}}\) - 1

=\(\frac{1}{5^2}\) -1

=\(\frac{1}{25}-1=\frac{-24}{25}\)