## Expansions 1

ALGEBRA20040114

Each of these lines of algebra has exactly one error. Write the correct lines of algebra out in your book (don’t just correct the sheet). Enough is left correct (and in nearby questions) for you to use as strong hints. While some pupils prefer to ignore the ‘wrong’ right hand side, don’t ignore it completely. This sheet should prove rather easy and help you to be confident; the next sheet is harder.

1   (x + 3) (x  + 4)       =   x²   +  7x  +  34

2   (2x + 3) (2x – 3)     =   4x²   - 6

3   (14x + 10) (14x – 10)       =   169x²   - 100

4   (3x + 5) (2x – 7)   =   5x²   + 10x - 21x – 35  =  5x²   - 11x – 35

5   (x  -  y) (x  –  2y)    =   x²   - 3xy  –  2y²

6   (y -  2p) (y – 3p)   =   y²   -  6yp  +  6p²

7   (3– q) (5 – 2q)   =   15  - 30q  –  2q²

8   (x² + 3) (x³ + 5)  =   x⁵  +  8x2.5    + 15

9   (x  + 2) (x  + 4) =    x24   +2 x  + 2 x + 8

10  (x² -  1) (x² + 1)  =     x   -   2

11  (x + 1/x) (x + 2/x)  =    x²   +  3x  +   2 / x²

12  (3 + 1/x) (2 -1/ x² =     6 +  2/x  -  2/x²  -  1/x³

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