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3 years ago

Solve by completing the square: x^2+15=8x

1 answer:

3 0

x^2+15=8x
x^2-8x=-15
x^2 - 2 (x)(4) =-15
adding 16 on both sides
x^2 - 2 (x)(4) +16=-15+16
x^2 - 2 (x)(4) + 4^2= 1

(x-4)^2=1

taking square root on bothsides x-4 = +-1
so x-4=1 or x-4=-1
x-5 or x=3

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Strike441 [17]

Answer:

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General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Equality Properties

Step-by-step explanation:

Step 1: Define

$\displaystyle \frac{6}{19} = \frac{x - 12}{2x - 2}$

Step 2: Solve for x

Cross-multiply: $\displaystyle 6(2x - 2) = 19(x - 12)$
Distribute: $\displaystyle 12x - 12 = 19x - 228$
Isolate x terms: $\displaystyle -12 = 7x - 228$
Isolate x term: $\displaystyle 216 = 7x$
Isolate x: $\displaystyle \frac{216}{7} = x$
Rewrite: $\displaystyle x = \frac{216}{7}$

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