Carol has only 20p and 10p coins in her purse she has three times as many 20p coins and 10p coins if Carol has ?4.20 altogether,
2 answers:
Suppose that Carol has x 10p coins in her purse. Since she has three times as many 20p coins as 10p coins, then she has 3x 20p coins in her purse.
x coins of 10p value $0.10x and 3x coins of 20p value $0.60x.
In total this amount of money is $(0.10x+0.60x)=$0.70x that is exactly $4.20. Thus, you get the equation
0.70x=4.20.
Solve it:
Carol has 6 coins of 10p and 3·6=18 coins of 20p.
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It is often more convenient to evaluate a polynomial when it is written is "Horner form."
... f(x) = (((10x -4)x -8)x +3)x -6
The graphs offered can be distinguished by their values of f(1) and f(2), so our table can be a short one.
... f(1) = (((10·1 -4)1 -8)1 +3)1 -6 = -5 . . . . . . . eliminates graph d
... f(2) = (((10·2 -4)2 -8)2 +3)2 -6 = 96 . . . . eliminates graphs a and c
The appropriate choice is b.
