`(0.7x-0.9)/(0.3x-0.7)=9`

(0.9x+0.7y)(0.81x^2-0.63xy+0.49^2) =………….

Find the following products: (i) (0.9x+0.7y)(0.81x^(2)-0.63xy+0.49y^(2)) (ii) ((2x)/(5)-(3y)/(7))((9y^(2))/(49)+(4x^(2))/(25)+(6xy)/(35))

Find the product: (0.9x+0.7y)(0.81x^(2)-0.63xy+49y^(2))

Lt_(x to 0) (cos7x-cos9x)/(cos3x-cos7x)=

If the cofficients of x^(2) and x^(3) in the expansion 0(3+ax)^(9) are the same,then the value of a is -(7)/(9) b.-(9)/(7) c.(7)/(9) d.(9)/(7)

underset(x to 0)"Lt" (cos 7x-cos 9x)/(cos 3x-cos 7x)=

Find the product: (0. 9 x+0. 7 y)(0. 81 x^2-0. 63 x y+0.49 y^2)

{:(0.4x + 0.3y = 1.7),(0.7x - 0.2y = 0.8):}

{:(0.4x + 0.3y = 1.7),(0.7x - 0.2y = 0.8):}

lim_(x rarr0)(cos7x-cos9x)/(cos x-cos5x)