Question

what must be added to 3x-7 to make x^2+4x-1

Answer 1

Let the unknown part be represented by

A

Then we have:

3

x

−

7

+

A

=

x

2

+

4

x

−

1

Subtract

3

x

from both sides

−

7

+

A

=

x

2

+

4

x

−

3

x

−

1

but

4

x

−

3

x

is

x

giving:

−

7

+

A

=

x

2

+

x

−

1

Add 7 to both sides

A

=

x

2

+

x

+

6

So you need to add:

x

2

+

x

+

6