Page 53 - 新思维数学学生用书9 样章

2 Expressions and formulae

Check your progress

1 Work out the value of each expression when x = 3, y = 5 and z = −2.
a x(3y + z) b (2x) + y 3 c (x + ) y − z 5
2
4
2 Write an expression for the perimeter and area of this rectangle. 5x
Write each answer in its simplest form. 3x + 4
3 Simplify each expression.
a x × x 3 b q ÷ q 2 c (h )
8
2
2 5
d 3m × 5m 2 e 12u 3 5 f 4p – p 2
7
2
6u
4 Expand and simplify each expression.
a (x + 2)(x + 5) b (x − 3)(x + 4) c (x + 6)(x − 9)
d (x − 10)(x − 4) e (x − 8)(x + 8) f (x − 6) 2
5 Simplify each expression.

a x + x b y − y c 3x − y d 9x − 15
3 3 5 15 5 20 3
6 a Use the formula x = y + 5z to work out the value of x when y = 4 and z = 3.
2
b Make z the subject of the formula. Work out the value of z when x = 55 and y = 5.
c Make y the subject of the formula. Work out the value of y when x = 46 and z = 2.

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