Question

Subtract $-{\mathrm{m}}^2+5\mathrm{mn}$ from $4{\mathrm{m}}^2-3\mathrm{mn}+8$.

Answer 1

We have to subtract $-{\mathrm{m}}^2+5\mathrm{mn}$ from $4{\mathrm{m}}^2-3\mathrm{mn}+8$.

$$\begin{gathered} \left(4{\mathrm{m}}^2-3\mathrm{mn}+8\right)-\left(-{\mathrm{m}}^2+5\mathrm{mn}\right) \\ =4{\mathrm{m}}^2-3\mathrm{mn}+8+{\mathrm{m}}^2-5\mathrm{mn} \\ =4{\mathrm{m}}^2+{\mathrm{m}}^2-3\mathrm{mn}-5\mathrm{mn}+8 \\ =5{\mathrm{m}}^2-8\mathrm{mn}+8 \end{gathered}$$

Therefore the required answer is $5{\mathrm{m}}^2-8\mathrm{mn}+8$.