Solve the system of equations using the substitution method. 2x+y=8
y=x-1

x=3

Step-by-step explanation:

If we know that y=x-1, we can just substitute it and replace y with (x-1)

so 2x+y=8 becomes:

2x+(x-1)=8 and we simplify that into:

3x-1=8, add 1 on both sides to make it:

3x=9, divide 3 on both sides

x=3

- 2 + 10x³ - 21x² + 19x - 4

step-by-step explanation:

each term in the second factor is multiplied by each term in the first factor

x²(- 2x² + 4x - 1) - 3x(- 2x² + 4x - 1) + 4(- 2x² + 4x - 1) ← distribute

= - 2 + 4x³ - x² + 6x³ - 12x² + 3x -8x² + 16x - 4

collect like terms

= - 2 + 10x³ - 21x² + 19x - 4 ← in standard form