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C1 help

Can someone please help me solve this

solve the equation
1) x^3 + 8 = 9x^3/2

2)Express x^2 + 6x + 7 in the form (x + a)^2 + b.

Reply 1

sabuuk

zoo91

Can someone please help me solve this

solve the equation
1) x^3 + 8 = 9x^3/2

2)Express x^2 + 6x + 7 in the form (x + a)^2 + b.

1) collect like terms and then cube root to find x.....

2) Try completing the square

Reply 2

Rob da Mop

zoo91

Can someone please help me solve this

solve the equation
1) x^3 + 8 = 9x^3/2

2)Express x^2 + 6x + 7 in the form (x + a)^2 + b.

First, is it (x^3)/2 or x^(3/2)?

The second is completing the square. Half the co-efficient of x and place it as a, then take a^2 from the constant and place that as b.

Reply 3

zoo91

Rob da Mop

First, is it (x^3)/2 or x^(3/2)?

The second is completing the square. Half the co-efficient of x and place it as a, then take a^2 from the constant and place that as b.

it is x^(3/2)

Reply 4

gcseeeman

zoo91

Can someone please help me solve this

solve the equation
1) x^3 + 8 = 9x^3/2

2)Express x^2 + 6x + 7 in the form (x + a)^2 + b.

For the first, you could make it equal zero and factorise, but it is probably nicer to make a substitution (e.g.

x^3 = y^2

), then you get a simple quadratic in y which should be easy to factorise/solve.

Like others have said, for the second complete the square.

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