Advertisements
Advertisements
Question
Multiply and then evaluate:
(4x + y) and (x – 2y); when x = 2 and y = 1.
Advertisements
Solution
(4x + y) × (x − 2y)
= 4x (x − 2y) + y (x − 2y)
= 4x2 − 8xy + xy − 2y2
= 4x2 − 7xy − 2y2
Verification:
When x = 2, y = 1
L.H.S. = (4x + y) (x − 2y)
= (4 × 2 + 1) (2 − 2 × 1)
= (8 + 1) (2 − 2)
= 9 × 0
= 0
R.H.S. = 4x2 − 7xy − 2y2
= 4 (2)2 − 7 × 2 × 1 − 2 (1)2
= 4 × 4 − 14 − 2
= 16 − 16
= 0
∴ L.H.S. = R.H.S.
APPEARS IN
RELATED QUESTIONS
If m = 2, find the difference between the values of 4m3 and 3m4.
Evaluate:
(23 – 15) + 4
Evaluate:
6m – (4m – m)
Evaluate:
(9a – 3a) + 4a
Simplify:
− (y − x) − (x + y − `overline(2"x"+"y")`)
Simplify:
3x − [5y − {6y + 2 (10y − x)}]
Fill in the blank:
2t + r − p − q + s = 2t + r − (..................)
If P = − 12x2 – 10xy + 5y2, Q = 7x2 + 6xy + 2y2, and R = 5x2 + 2xy + 4y2 ; find P + Q + R
Multiply and then evaluate:
(x – 2y + z) and (x – 3z); when x = − 2, y = − 1 and z = 1.
Simplify:
2 (3x2 – 4x – 8) – (3 – 5x – 2x2)
