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3 years ago

Solve by factorising x^2 + 8x + 15 = 0

Mathematics

1 answer:

Nutka1998 [239]3 years ago

3 0

Answer:

See below

Step-by-step explanation:

x² + 8x + 15 = 0

x² + 5x + 3x + 15 = 0

x x (x + 5) + 3x + 15 = 0

xx (x + 5) +3 (x + 5) = 0

(x + 5) × (x + 3) = 0 → x + 5 = 0 x + 3 = 0

x = -5

x + 3 = 0

x = -5

x = -3

x1 = -5

x2 = -3

Hope this helped ! :)

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(1/27)^x-6=27 Could I please have a step by step as well? Much appreciated!

Andrei [34K]

Answer:

$x = 7$

Step-by-step explanation:

1) Use Division Distributive Property: (x/y)^a = x^a/y^a.

$\frac{1}{ {27}^{x - 8} } = 27$

2) Multiply both sides by 27^x - 8.

$1 = {27} \times 27^{1 + x - 8}$

3) Use the product rule: x^a x^b = x^a+b.

$1 = {27}^{1 + x - 8}$

4) Simplify 1 + x - 8 to x - 7.

$1 = {27}^{x - 7}$

5) Use Definition of Common Logarithm: b^a = x if and only if logb (x) = a.

$log_{27}1 = x - 7$

6) Use Change of Base Rule.

$\frac{ log_1 }{ log{27} } = x - 7$

7) Use rule of 1: log 1 = 0.

$\frac{0}{ log_{27}} = x - 7$

8) Simplify 0/log_27 to 0.

$0 = x - 7$

9) Add 7 to both sides.

$7 = x$

10) Switch sides.

$x = 7$

Therefor, the answer is x = 7.

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