如图,已知抛物线y=ax2 bx c,经过点a(-3,0),b(1,0)(1)求抛物线的解析式 (2)若抛物线
已知抛物线y=ax2 bx c,经过点a(-3,0),b(3,0),c(1,0) 1、由点a,c = 3;由点B,9a 3b 3 = 0,3a b 1 = 0 ? ? ?由点c, a b 3 = 0;两式相减 ? 2a - 2 = 0 ? ? ?a = 1; ? b = - a - 3 = - 4; 抛物线的解析式 ? y = x^2 - 4x 3 2、y = x^2 - 4x 3 = x^2 - 4x 4 - 1 = (x - 2 )^2 - 1,顶点p ( 2,- 1 ); ∠pac = ∠pao - ∠cao = tg^-1( 1/2 ) - tg^...全部
已知抛物线y=ax2 bx c,经过点a(-3,0),b(3,0),c(1,0) 1、由点a,c = 3;由点B,9a 3b 3 = 0,3a b 1 = 0 ? ? ?由点c, a b 3 = 0;两式相减 ? 2a - 2 = 0 ? ? ?a = 1; ? b = - a - 3 = - 4; 抛物线的解析式 ? y = x^2 - 4x 3 2、y = x^2 - 4x 3 = x^2 - 4x 4 - 1 = (x - 2 )^2 - 1,顶点p ( 2,- 1 ); ∠pac = ∠pao - ∠cao = tg^-1( 1/2 ) - tg^-1( 1/3 ) = 8。
13度; tg 8。13度 = 1/7。收起