Approximate conversions for cooking are ...
1 tsp ≈ 5 mL, so 1/2 tsp is about 2.5 mL
1 Tbsp ≈ 15 mL
1 cup ≈ 240 mL, so 1 1/2 cups ≈ 355 mL*
1 1/2 lb ≈ 680 g
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* 1 cup is about 236.6 mL.
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Many cookbooks have tables of equivalents.
Consider the polynomial identity (difference of squares):
(x+y)(x-y) = x² - y²
Set x =7 and y = 2 to obtain
(7+2)*(7-2) = 7² - 2²
9*5 = 49 - 4
45 = 49 - 4
This is the result required, obtained by using difference of squares.
Answer: Difference of squares.
First you would need to combine like terms. do you know how to do that?
