2 × 4.2 - 1.9 x 1.9=2.3 x 6.1 x 6.3 x 6.3 x 6.1
A. 0.5
B. 1.0
C. 20
D. 22
Answer:B
2 × 4.2 - 1.9 x 1.9=2.3 x 6.1 x 6.3 x 6.3 x 6.1
A. 0.5 B. 1.0 C. 20 D. 22
Explanation: = (a2 - b2) /(a + b)(a - b)= (a2 - b2)/(a2 - b2) = 1.