Uma maneira de realizar a operação 9972 - 9 de forma rápida e correta é calculando 1 000 * 994, que é igual a 994 000. A igualdade que justifica esse fato está expressa em: a) (a + b)² = a² + b² + 2ab
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b) a² - b² = (a + b)(a - b)
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c) a² - b² = (a - b)²
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d) (a - b)² = a² - 2ab + b²
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e) a² - b² = 1 000(a + b)

A=1/2h(b1+b2) is the formula for the area of a a trapezoid b regular polygon c triangle d rhombus or kite

Can someone me with this problem i don't understand i need

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?