Question

solve the equation using identity [x+a] [x+b].
question
​1.[4x-5][4x-5]

Answer 1

$$\begin{gathered} \left(4\mathrm{x}-5\right)\left(4\mathrm{x}-5\right) \\ =\left[4\mathrm{x}+\left(-5\right)\right]\left[4\mathrm{x}+\left(-5\right)\right] \\ ={\left(4\mathrm{x}\right)}^2+\left[\left(-5\right)+\left(-5\right)\right]\left(4\mathrm{x}\right)+\left(-5\right)\times \left(-5\right)\left[\mathbf{as}\mathbf{,}\mathbf{}\left(\mathbf{x}\mathbf{+}\mathbf{a}\right)\left(\mathbf{x}\mathbf{+}\mathbf{b}\right)\mathbf{}\mathbf{=}\mathbf{}{\mathbf{x}}^{\mathbf{2}}\mathbf{}\mathbf{+}\mathbf{}\left(\mathbf{a}\mathbf{+}\mathbf{b}\right)\mathbf{x}\mathbf{}\mathbf{+}\mathbf{}\mathbf{ab}\right] \\ =16{\mathrm{x}}^2+\left(-10\right)\left(4\mathrm{x}\right)+25 \\ =16{\mathrm{x}}^2-40\mathrm{x}+25 \end{gathered}$$