## solve by completing the square method 3x²=15-4x

Question

solve by completing the square method 3x²=15-4x

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Mathematics
3 days
2021-07-20T04:38:17+00:00
2021-07-20T04:38:17+00:00 2 Answers
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## Answers ( )

Answer:x = – 3, x =

Step-by-step explanation:Given

3x² =15 – 4x ( add 4x to both sides )

3x² + 4x = 15 ← factor out 3 from each term on the left side

3(x² + x) = 15

To complete the square

add/subtract ( half the coefficient of the x- term)² to x² + x

3(x² + 2( )x + – ) = 15

3(x + )² – = 15 ( add to both sides )

3(x + )² = 15 + = ( divide both sides by 3 )

(x + )² = ( take the square root of both sides )

x + = ± = ± ( subtract from both sides )

x = – ± , then

x = – – = – 3

x = – + =

Answer:Step-by-step explanation:3x²=15-4x

divide by 3 on both sides

x²=5-x

move everything to one side

x²+x -5 = 0

add the square of 1/2 the middle term of but also subtract it too

x²+x +-5- = 0

now use the property of a perfect square to rewrite

-5 – = 0

rewrite 5 as a fraction

– – = 0

add up the fractions

– = 0

move to the other side

=

take the square root of both sides 😛

=

much easier looking now, just use algebra to solve for x

x + =

subtract from both sides

x + – = –

x =

🙂