a) 142 – 11 mũ 2x+1 : 11 = 21 b) 4 mũ 2x+1 – 14.4 = 8 c) 3 mũ x – 1 + 2.3 mũ x = 7 d) 3 mũ x + 4 mũ x = 7

Question

a) 142 – 11 mũ 2x+1 : 11 = 21 b) 4 mũ 2x+1 – 14.4 = 8 c) 3 mũ x – 1 + 2.3 mũ x = 7
d) 3 mũ x + 4 mũ x = 7

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Ximena 4 tuần 2021-07-11T00:52:49+00:00 1 Answers 3 views 0

Answers ( )

    0
    2021-07-11T00:54:27+00:00

    Giải thích các bước giải:

     $a)142-11^{2x+1}:11=21$

    $⇔142-11^{2x+1}:11^1=21$

    $⇔11^{2x+1-1}=142-21$

    $⇔11^{2x}=121$

    $⇔11^{2x}=11^2$

    $⇔2x=2$

    $⇔x=1$

    $\text{Vậy $x=1$}$

    $b) 4^{2x+1}-14.4=8$

    $⇔4^{2x+1}-56=8$

    $⇔4^{2x+1}=64$

    $⇔4^{2x+1}=4^4$

    $⇔2x+1=4$

    $⇔2x=3$

    $⇔x=\dfrac{3}{2}$

    $\text{Vậy $x=\dfrac{3}{2}$}$

    $c)3^x-1+2.3^x=7$

    $⇔3×3^x-1=7$

    $⇔3^{x+1}-1=7$

    $⇔3^{x+1}=8$

    $⇔3^{x+1}≈3^{1,9}$

    $⇔x+1≈1,9$

    $⇔x≈0,9$

    $\text{Vậy $x≈0,9$}$

    $d)3^x+4^x=7$

    $⇔3^x+4^x=3+4$

    $⇒x=1$

    $\text{Vậy $x=1$}$

    Học tốt!!!

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