Page 37 - 新思维数学活动用书7 样章

2 Expressions, formulae and equations

For each of these diagrams:

i Write an equation involving the angles.
ii Simplify your equation by collecting like terms.
iii Solve your equation to find the value of x.
iv Work out the sizes of the angles in the diagram.

v Check that your answers are correct by substituting your answer
back into the original equation.
a b Tip
What do the

5x 6x 4x angles on a
4x straight line and
c d in a triangle add
5x
up to?
3x 4x 2x 3x 4x

11 Solve each of these equations and check your answers.

a x + 12 = −6 b y − 9 = −4
c 3z + 6 = −30 d 4w − 3 = −27
12 Zara solves these equations:
2a − 11 = −7 4 = b + 16 I think that

6c + 7 = 25 −12 = 3d + 9 a × b < c + d
Is Zara correct? Show all your working and
explain your answer.

13 Use the formula w = 2x + y − 3z to work out:
a w when x = 8, y = −3 and z = 7
b x when w = 15, y = 9 and z = −4

c y when w = −10, x = 6 and z = 2
d z when w = 20, x = 15 and y = 8

36