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Expand (x - 7) (6-x)

publish date2020/11/21 19:02:00 GMT+11

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a.    x+ 13x - 42

b. −x2 + 7x − 42

c. −x2 + 13x − 42

d. −x2 + 13x − 13

a
b
c
d

Correct Answer

c

Explanation

  1. Write the expression.
    • (x − 7)(6 − x)
  2. Multiply the first terms in each bracket, then the outer terms, the inner terms and finally the last terms.
    • = x × 6, x × −x, −7 × 6, −7 × −x
  3. Remove the brackets by multiplying each term in the brackets by the term outside the bracket. Remember to change the sign when the term outside the bracket is negative.
    • = 6x − x2 − 42 + 7x
  4. Collect like terms.
    • = −x2 + 13x − 42

Reference

Maths_Quest_10+10A_VC_Revised_Edition_Book


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