Đáp án:
Giải thích các bước giải:
1.9
a) (2x - 3 )² =25
⇔ (2x - 3 )² = 5²
⇔ 2x-3 = 5 ⇔ 2x=8 ⇔ x=4
b) (5x +1 ) ∧ 4 =32
⇔ (5x+1) ∧ 4 = 2∧4
⇔ 5x+1=2 ⇔ 5x =1 ⇔ x=$\frac{1}{5}$
c) (2x+1)∧5 = (2x+1)∧100
⇔ ( 2x+1)∧100 - (2x+1)∧5 =0
⇔ (2x+1)∧5 × ( ( 2x+1)∧95 -1 ) =0
⇔\(\left[ \begin{array}{l}(2x+1)^5=0\\(2x+1)^95-1=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}2x+1=0\\(2x+1)^95=1\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=-1/2\\2x+1=\end{array} \right.\)⇔ \(\left[ \begin{array}{l}2x+1=1\\2x+1=-1\end{array} \right.\)
⇔ x= -1/2 hoặc x=0 hoặc x= -1
d) (x-$\frac{1}{2}$ )^3 =$\frac{1}{27}$
⇔ (x-1/2) ^3 = (1/3)^3
⇔ x-1/2 = 1/3
⇔ x= 5/6
1.10
a) 3^x-1 = 1/243
⇔ 3^x-1 = 3^-5
⇔ x-1 = -5 ⇔ x= -4
b) 81^-2x × 27^x = 9^5
⇔ 3^-8x × 3^3x = 3^10
⇔ 3^-24x = 3^10
⇔ -24x = 10 ⇔ x= -5/12
c) 64/169 = (-8/13)^x
⇔ (-8/13)² = (-8/13)^x
⇔ x=2
d) $\frac{7^x+1}{49^x}$ = 49^2
⇔ 7^x+1 = 49 ^x+2
⇔ 7^x+1 = 7^2x +4
⇔ x+1 = 2x+4
⇔ x=-4
e) (1/2)^2x-1 = 1/8
⇔ (1/2)2x-1 = (1/2)^3
⇔ 2x-1 = 3 ⇔ 2x=4 ⇔ x=2
f) 2^x × 4 =128
⇔ 2^x × 2² = 2^7
⇔ 2^x+2 = 2^7
⇔ x+2 = 7 ⇔ x=5
g)7^2+x +2×7^x-1 = 345
⇔ 7^x-1+3 +2 × 7^x-1 =345
⇔ 7^x-1 ×( 7³ +2 ) =345
⇔ 7^x-1 × 345 =345
⇔ 7^x-1 =1
⇔ 7^x = 8 ( vô lí )
h) Giống câu b
Cho mik 5* nha
