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2^x + 2^x × 2^3 = 72
2^x (1 + 2^3) = 72
2^x × 9 = 72
2^x = 8
x = 3
b.) 3^x + 3^(x+2) = 90
3^x + 3^x × 3^2 = 90
3^x (1 + 9) = 90
3^x = 90/10
3^x = 9
x = 2
c.) 4^(x+1) + 2^(2x) = 20
(4^x × 4) + 4^x = 20
4^x (4 + 1) = 20
4^x = 4
x = 1
d.) 2^x - 2^(x + 2) = -12
2^x - 2^x × 2^2 = -12
2^x (1 - 4) = -12
2^x = 4
x = 2
e.) 3^(x^2 - 5) - 9^(x - 1) = 0
3^(x^2 - 5) = 9^(x - 1)
3^(x^2 - 5) = 3^(2(x - 1))
3^(x^2 - 5) = 3^(2x - 2)
x^2 - 5 = 2x - 2
x^2 - 2x - 3 = 0
(x-3)(x+1)
x = 3; x = -1
f.) 5^(x^2 + 3) - 25^2x = 0
5^(x^2 + 3) = 25^2x
5^(x^2 + 3) = (5^2)^2x
5^(x^2 + 3) = 5^4x
x^2 + 3 = 4x
x^2 - 4x + 3 = 0
(x-3)(x-1)
x = 3; x = 1
Kalo kurang jelas, tanyakan saja :D
(1 + 2)³ x 2ˣ = 72
9 x 2ˣ = 72
2ˣ = 8
x = 3
b) 3ˣ + 3ˣ⁺² = 90
(1 + 3²) x 3ˣ = 90
10 x 3ˣ = 90
3ˣ = 9
x = 2
c) 4ˣ⁺¹ + 2²ˣ = 20 ===> 4ˣ⁺¹ diubah ke 2²ˣ⁺²
2²ˣ+² + 2²ˣ = 20
(2² + 1) x 2²ˣ = 20
5 x 2²ˣ = 20
2²ˣ = 4
2²ˣ = 2² ===> 2x = 2 ===> x = 1
d) 2ˣ - 2ˣ⁺² = -12
(1 - 2²) x 2ˣ = -12
(-3) x 2ˣ = -12
2ˣ = 4
x = 2
e) 3ˣ² ⁻⁵ - 9ˣ⁻¹ = 0
3ˣ² ⁻⁵ = 9ˣ⁻¹
3ˣ² ⁻⁵ = 3²ˣ⁻² ===> x² - 5 = 2x - 2
x² - 2x - 3 = 0
gunakan rumus abc, maka x₁ = 3 dan x₂ = -1
f) 5ˣ² ⁺³ - 25²ˣ = 0
5ˣ² ⁺³ = 25²ˣ
5ˣ² ⁺³ = 5⁴ˣ ===> x² + 3 = 4x
x² - 4x + 3 = 0
(x - 3)(x - 1) = 0
x₁ = 3 dan x₂ = 1
semoga jelas dan membantu ya